Why get rid of the NSG370? Is it bad or does it need a rebuild? IMHO, not worth the effort of the swap for no real increase in strength. What do you hope to gain by the swap? If you were going to an automatic or something heavier, I'd understand but otherwise it's a lot of labor for little to no gain if you think about it.
Don't get me wrong here, I like the AX-15 myself but you still have to ask yourself at what benefit does the effort gain you?
RR