Poly 4.1 Challenger comes in 3 base models and 50hp Honda weighs 100kg.

Open boat @ 280kg.... 280+100 = 380/50 = 7.6 kg/hp

Side console @ 295kg.... 295 + 100 = 395/50 = 7.9 kg/hp

Centre console @ 305 kg....305 + 100 = 405/50 = 8.1 kg/hp

All three configurations not the best. I'd be looking for 7 or lower.

4.1 Challenger rated @ 50hp so can't go up to 60hp without formal compliance plate modification. If so..60 hp on a 4.1 open @ 280kg....280 + 110 = 390/60 = 6.5 kg/hp

Unless it can be re-plated I'd look further as the starting point not so good.