I'd agree. The added power drag of the 4wd gear is going to heavily tax the 235. If you want the engine bay to look "original" I'd build a modified 250 or 292 that will bolt on to the TH350 as mentioned above.

'69 1/2T stepside, Sea Foam Green, 250 L6 w/ 3 on the tree, not an option on it, in the family since new.