This covers most of the options
http://members.iinet.net.au/~stepho/celfaq.txt
I haven't mentioned an '85 directly but the options are pretty much the same as for the '77 RA29.
Adding a heavy engine too far up front will screw up your handling.
Avoid 6 cylinder engines and cast iron V8 engines unless you can cut out the firewall and relocate the whole engine way back.
A modified 22R engine is the best bet for reasonable cost.
The other engines can be done but might be a bit complicated for your first engine swap.
- Stepho
http://members.iinet.net.au/~stepho/celprod.htm
