Crikey - that's quite a tall order.
The only place I'm aware of that could help with the engine is Nicholson McLaren - I
believe they've done some RBAR prep and they are a Continental approved outfit and have an excellent reputation:
Experimental Engines | Nicholson McLaren
They won't be cheap but at least it won't go bang. Hopefully. If it does, at least you can admire the quality parts whizzing past the canopy.
As for tweaking the aerodynamics - assuming you don't require a wind tunnel for serious tweaks (!) then Pete Wells at Zulu Glasstek has done some fairing work on RBAR machines and has a wealth of experience in metal and particularly composite. His workmanship is absolutely first class so if you're looking for a new cowling and some tidying up he'd be perfect. I expect he'll know the ropes with LAA approval as well of course.
Zulu Glasstek - Composite Repairs, C of A work, instrument fitting and painting for Gliders & Sailplanes, UK agents for Alexander Schleicher Sailplanes and Silence Aircraft
I expect our American cousins are much more current with this sort of tweaking - might be worth seeking some advice there?