My clutch side knee is bothering me again so it looks like manual trans will not be in the future for me so makes the adapter to put a auto trans behind a 235,it looks like I will have to make or buy side mounts for the engine but the new 235 that will be going in has the provisions on the block.
Get a Buffalo or Speed Gems plate and flex plate. Speedway and other Circle Track suppliers sell a 3 Bolt rear SBC side “wing” that attaches to the same bolts the trans attaches to (we use studs.. about $60. You can get angle mounts to your frame or make your own from angle iron; then use Ford flathead front donut mounts.
At the shop I work at is all the parts I need but will not come off of those parts,they put a TH 400 behind a 235 but who they had driving it could not handle it so they did a LS swap but those parts will be sitting there for years. I am done waiting for a answer so time to find my own parts.
Turbo 400 takes a lot of hp for a 235. Depending on the car weight the cheapest trans would be an air cooled PG from 62 up 6 cylinder Chevy II or Chevelle. Water cooled the best but actually not needed in a light car. GM used thousands of the and most went close to 100k miles if treated right.
I went down this road a while back, and by chance happened across a 194 Chevy 6, which has the flange at the back of the block to take the Powerglide-T350/400/700 auto trans. If you haven't got the 235 yet, this combination would be an easier (and cheaper) option. The 250 L6 and a couple of others are the same version of engine. The side mounts for the 194/250 are fairly simple to fabricate.
I had a thought on how to make a 216/235/261 family 6 cylinder bell pattern adapt to the typical PG,350,400,700r4 bell pattern. My idea was to use the adapter of a SBC to Cast iron PG, AND a 235 to Cast iron PG adapter. Install the 235 adapter to the 235 engine, then install the 235 flex plate AND a crankshaft spacer to the crankshaft. Spacer needs to be long enough to mount the flex plate of the newer transmission torque converter at the correct position. Next mount the SBC adapter to the 235 adapter using the Cast iron PG flanges of both adapters. This will now allow the newer transmissions to be mounted. I know it sounds crazy, but it may be possible.
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