Some observations of mine over the years spent getting our car back on the road....and some efforts of others!
Front A-arms: Your early car likely has "rev-A" lower arms. These have metal strip welded along bottom of tube(s) but stops short of the ball joint cup. This is where they are known for failure...cup busts right off. Rev-B arms used a metal "U" channel about 3/8" or 10mm square which is welded along the bottom at intervals, and extends over the BJ cup area strengthening the whole mess. I had one of each on my car due to accident...welder could only find solid bar to use, but I think "U" style is available if ya look...... (MSC ???)
Front Lower Bushings: Inspect and fab replacements as needed. I put some new ones in.....but they didn't offer much improvement if any, over the old ones! They do need some lube all over everything to prevent squeaks....there are no grease zerks here.....luckily you can just lift the corner of the car to unload the suspension and the two bolts can be removed allowing the lower arm to be dropped for servicing.....doesn't affect any alignment.
Ball Joints: Inspect for blown apart ball joints. Originals appear to be two pieces of stamped steel welded at the edges. You can expect multiple pieces to fall out if you still have originals. New ones are cast units- Fiat 124 uppers if memory serves me. DO NOT grind the a-arm cups to accept new ones...... get the proper ball joints...! They are out there and readily available.
Rear A-arms are a little more beefy- I had no issues with these.... Often bent from idiots raising car with jacks under arms......!
Trans support: Lots said about this, but only one modification I would accept on these cars, which is to add inboard connections for the ladder bar at the top of the shock towers. (Inboard about 5-4" from outer upper shock bolts.) This will "help" prevent catastrophic failure if the shock tower cracks! Don't ask how I know this...... Easy enuf to do.
The bushings at the outer ends of the trans cross member are the same as the stock shock absorber bushings....if you have any good left in them.....but these bushings usually stand up better in the crossmember position! Not sure of availability any longer....you may need to fab something up!
I added a small stiffener bar between the outer mounts of the trans crossmember to prevent "some" amount of frame flex.... I know that other solutions have been suggested for preventing "Z" flexing of the chassis under hard cornering...it's real.....but quite frankly, it's way easier just not to "hard corner".....! After all, you are driving a 401K plan that has performed handsomely over time....no need to trash it senselessly now! IMHO, if you NEED to go hard cornering, buy a different DeTomaso or a late model 5L car and have at it..... Drive your GOose in a gentile and stately manner around curves! )) You will look fantastic doing it!!!!
Steering rack: While the RHD cars allegedly had a swap rack to drop the ratio, I have not heard of any for the LHD Goose. In my experience, after now driving a Pantera for a while, the Goose rack feels very comfortable compared to the lower ratio in the Pantera. Not ideal for close corner fast-slow speed maneuvering, but since you are carving the corners off of your new tires, and stressing all of your frame member attachments, just don't do it. Your car looks fast sitting still....... The higher ratio rack makes the car easier to control in and out of parking spots!
Bump Steer: Ugh. We have one or two members here with extensive frame/steering knowledge that set out on an effort to cure this issue. The results were either epic failure, or "it fixed some of it". The latter required machining of the outer steering rod on the spindle, spacers for the tie rod ends.....and perhaps a little more. More than most would like to undertake....perhaps. Attempts to raise or lower the rack find interference from the frame in every direction! Wholesale redesign of the front frame members required. Not going there!
I would think that when doing close to triple digits on a bumpy road is where bumpsteer would be an issue...and not on smooth roads. So, stay off of bumpy roads when driving fast! Your chassis will love you for it!! ))
Love the car for it's beauty....forgive it for the defects, and "drive around" the bumps!!