[Jay S]

200R4 is the easiest overdrive swap in this. It is the only OD tranny that is a direct bolt in from a TH350, same driveshaft, same transmission yoke, no bell housing adapter, speedometer hooks up stock, no electronics, add a TV cable and it is mostly done. Takes some upgrades to make them hold up to a 455, an Art Carr 200R4 is rated from 750HP for something like $3700, which is overkill on this, but a really nice transmission. Most shops can build a 200R4 cheaper than that for a 450HP combo.

I mentioned the 700R4 earlier only because I thought the 3.06 first gear would help get the car moving with the 2.73s the car has now with the 8.2 BOP rear end and still work later if it got swapped to 3.73 gears to utilize the overdrive more. 700R4 is my least favorite of the GM overdrive’s though. 700R4 is geared better for a truck than a car IMHO. 4L80 is a nice heavy duty tranny to swap in, but it is a bit of a project (read JLmouce’s post).