Sometimes you have to hunt for a similar frame (to get stroke length) and sometimes there isn't a perfect match for the cylinder bore, but you can usually get in the ballpark with Ariel Perfomance on something like a HOSS, but it is never as good as the manufacturer's program.
the program is GE viper, i can't find where i got it, but I could send the 10.7MB files which include cylinder data base. o still use the Energy Industries (EI) dos based software, no problem. You can use ariel, but you'll need this link to get clearances and other data.
