Recommendations for engine/trans/rearend combos for 200 MPH Open Road racing.

if you "are" going standard trans the ZF s6-40 has a .45 6th which is what is installed in Bella! you find them in 92-6 corvettes!bellhousing is the holy grail, [holley $$ can make you one they have the specs] . Mated to a stroker with 3.23 gives you silverstate speed, I would put a paxton on it for the win unless it bumps you into a class that puts you up against supercars.
a diff. cooler might be necessary [not sure about that if only running 100miles]. I believe nascar runs a belt driven pump off the driveshaft but others methods [electric pump} may work!

I would likely start with a Gen III Hemi and trans pull-out, maybe a 6.1 or 6.4L. It likely will be less expensive than adding a bunch of the newer components like EFI, Overdrive, serpentine belt drive, High Amp alternator, Improved cooling system, newer P/S Pump, and A/C.
With the money saved on the engine, I to go with a RMS coil over K-Member/suspension/big brake kit.
This may not be perfect for 200 MPH as that may need more power, but should be good for at least 150 MPH. Once you are qualified for the higher speeds, add a blower to the engine.