The Merc 600s and nice purring V12 engines, so big they steer from the gearbox so the block stays still. Power to weight and prob £, the 450 Mercurys are suppose to be better. I do like the idea of duo props on outboards, they certainly have come a long way in last 10 yrs! R
Seems to be 2 trailers - one with black rollers and another with blue buffers. Which is it? As mentioned you should be able to adjust up.or down to work out what suits - to a certain degree as the eye on the bow will dictate how much. R
There are companies who specialise in this. I believe a modern diesel can blow seals and have fuel pump issues if running petrol. Hence, stop and have it dealt with, don't drive! Thus, I think there are a number of mobile specialists who come out and sort at your location. Good luck, Rob