I recently ran into this situation. I had a low mile 68 casting 318. I just pulled it apart and checked the bores, and replaced the rings and bearings. I replaced the cam with a 340 spec cam i bought here and used a spread bore intake I bought used also from this site. I have less than $250 tied up into it. It's not going to be a powerhouse by any means but a good dependable engine. Then again a pair of cheap e-bay turbos may find their way onto it.