why dont you just do that traxxas engine program thing where you give them your .15 + $100 and they give you everything you need to run your maxx with the new trx 2.5 engine.

-or-

you could sell your pro for $40-$60(at the most)

then just use that money towards a new engine

I actually think selling your engine, then getting the trx 2.5 engine will be cheaper than traxxas's engine swap deal.