How about this 360 LA combo?

C130 Chief said
Do a search here and on bigblockdart.com for subframe connectors. If the car was an auto from the factory, it had a 904. A 727 will basically bolt in, although there may be minor floor tweaking involved. Nothing outwardly visible.

As for quench, there are a few variables such as RPM, rod material and clearance. Generally you want no less than .030 and the effect goes away beyond .050 or so. A standard Fel-Pro composition head gasket has a compressed thickness of about .043, so most builders zero deck and call it good. Now, if you were to run reverse deflector pistons and open iron heads, some simple math might be needed. 10.5 compression with tight quench, and completely deburred aluminum heads should be fine on pump premium.

The car is almost completely original except for an aftermarket radio & 1 speaker. He!! it even had 1 of the old polished stainless OEM Anco wiper arms on it.

So the 904 IS the OEM transmission?

Would it be possible to beef 1 up enough to hold up behind 400+ crank HP? The nearest drag strip is 1 1/2 hours away so the car would not see that many full out 1/4 mile passes. 5 or 6 trips to the track a year would be about it.

I do not want to do anything non reversible. I'm not too enthused about modifying the tunnel. If I was willing to do that, I would just opt for a 4 speed or maybe even a T-56. I can live W/the subframe connecters. If done carefully I think they could be removed if my son ever decided to restore the car.