Most aftermarket rads have 1-1/2" straight stubs coming out of the core. Insert short pieces of 1-3/8" Gates Green stripe hose connected to 90 degree adapters with regular hose clamps. 90 degree sweat-solder copper tube fittings in the proper size work well. This allows you to space the 90 degrees out far enough to fit sucker fans. If your rad has formed stubs with 90 degree turns and you want to use the more efficient sucker fans in a shroud, cut the formed 90s off and insert short pieces of hose between the stubs and the 90s. Note- 1-3/8" rubber hose will expand enough with hot water to fit onto 1-1/2" stubs without much effort.
Part of the problem is, due to the body's low nose, the 16" tall Pantera radiator is shorter than- for instance- a 19" tall Corvette rad, both being 26" wide and both engines having similar power dumping about the same heat into their rads. If ANYTHING is off in your combination, many Panteras cannot cope with the smaller stock rad, at least at walking speeds. Once you're moving over about 30 mph, things work as DeTomaso planned. So we increase the water flow rate thru the system with a rad that has much larger tubes inside its core (1"-1-1/2" wide vs stock 3/8" wide), and use 2X or 3X bigger fans that suck 30mph air thru the entire core via a shroud, not just blow (less) air at two circles of the core.