I am saving up for a new motor for my 86 GXL.
Witch would be the best block out of the 13bT sereis should I use.
I am pretty knolegible in the swaps of all but witch is the most reliable and not **** to cooling problems and have the bigest ports.. I am not too crazy about having to send the housings out .

 

With regard to the issues you mention they're pretty much the same. There are changes in rotor weight and compresion, and minor strengthening on the later version, as well as many electrical changes on the later version.