Back in the day these where concidered the first "smog" motors, they were dogs. But that was in stock form. If you change the heads and cam you could get 300hp out of it. It would make a good first engine since you already have it. But I bet soon after you will want something better. I would look at that 350 first.
I put a 12 bolt Chevy under mine, There are some pics from my signiture, or the www button. Also here is an old post for some info:
http://www.hybridz.org/phpBB2/viewtopic.php?t=7763&highlight=straight+axle+drag+420
I installed a Vintage Air ,heat/def system. Nice and cold in the summer! I also installed cruise control for long trips, works great. Also a nice sound system, and sound deadner