On threaded freeze plugs, how much is piece of mind worth? Once bitten, twice shy.
A 1-1/2 NPT is currently $33.54 at Home Depot. You really want the non-tapered tap though and that you'll have to order and wait for.
The existing bore is perfect for it to start and it threads easily with a 15" Cresent wrench. Use plenty of oil on it.
I have the threaded plug just on my C8AE 302 block. I can't recall any issues installing them and just checked my tap and it was not modified but yes, it does come close to the bore sleeves.
My shop did my 351 at the time and installed brass press ins, but I'm tellin' ya', those things rust out from inside no matter what you do. 30 years on them is a long time.
It's just a thought to install them and if the block is in the shop anyway, why not ask how much to do them?
I do as much of my own work as I can and in addition my own brain surgery, although it does look like I need to redo my own pre-frontal lobotomy. I'm getting feisty again?
It is of interest to note, that even on the Ford installations, not all the plugs are seated 100% on the threads so it is normal for them to bottom against the bore liners.
I did notice that on this recent XE block, it did have threaded plugs in it.
Preparing an engine saying that you don't "need" certain items because you're never going to rev it past maybe 5,000 rpms and that they are overkill is silly.
IF you ever do a high speed track event in your STREET car, it's difficult to limit the engine to ONLY 7,000 rpm.
On the track that isn't much. You need to prepare it for maybe 8,000rpm, at least I do. That adrenaline is a killer. 
I'm using main studs and a girdle. In addition, shaft mounted Jessel type roller rocker arms