If the heads cracked then its garbage. 20R heads are hard to come bye at junkyards on the east coast.
Call junkyards and look for trucks and celicas from 75-79, they would have a 20Rwith spare head.
If you dont care about staying stock then pick up a 22R (carbed version) out of a celica or pickup from 80-83 These have pretty much identical emissions and electronics and have a double row timing chain and about 15hp more.
if you want to go turbo cheap pick up a 22RE from a 82-83 (double row timing chain) or a 22RE from 84-95 and buy the double row timing chain conversion from
www.lcengineering.com .
Ive got 2 76 coupes. One with the stock 20R and another with the firewall recessed back 6 inches and an 18RG DOHC motor from Japan (vintage race motor 145hp 8600rpm+ RL).
These cars are super cheap to build and have a lot of soul.
A great forum to check out is
www.classic-celica.com
Lots of info and everything from Honda Powered cars, to all out drag spec celics with Lexus V8s and SBCs or Turbo V6s.