Would it be wise to install an RB26 in the rx7? My main goal is to have speed and wheel spin for those corners

 

Um, sure? I'm not sure how any engine swap from another vehicle into a chassis it wasn't designed for can be considered "wise". Wisdom would often fall to the most practical engine replacement, which is the one the vehicle came with.

So you happen to have an decently running RB26 and an RX-7 that isn't running? And the time, skill and finances needed to make the swap? Then sure.