Dick, Kinky is right - there are better choices out there than a three speed. Try a late 5-speed manual or the earlier 4-speed OVERDRIVE toploader manual. I have one in my '85 van - it came standard w/a floor shift - very groovy.
C4, C6 or AOD autos are also around. Lots of choices.
Consider the earlier carbureted versions for your rod, unless you like EFI. Offy, Clifford, and others make carb intakes. Available on ebay complete w/ a carb for around $200. Good luck.