If you copy the existing modification (likely to need new engine mounts and propeller, as well as the engine) then the approval should be pretty straightforward so long as you're able to get hold of the design details and ensure they're copied completely, whilst your inspector has them to sign it off against.
LAA's likely to require a short test programme, probably 2-4 hours of real testing, and the remainder of probably 10 hours, flown off by yourself.
LAA will probably be able to point you at a suitable pilot to do the testing, but in your neck of the woods, the first person I'd ask would probably be India-Mike.
Expect the cost of conversion to have cost you a few hundred, maybe £500 in bits, paperwork and testing costs and the faff will take a few months.
G