Both the 75 and 70 are golden motors but the 75 is a detuned 90 and therefore a fair bit heavier I thin about 15 kilos, but I am sure some pedant will be along to correct me and tell it's 15.5
. A Yam 70 on a 4.7 is a magic combo in terms of power to weight and balance and if you can run it at WOT you will certainly have cahonnes.
re trailers You might want to consider having one from Extreme they will configure it to your spec and supply it flat packed for you to assemble if you wish. We did that abour 2 years ago and are very pleased with the trailer If I was going to buy another brand It would be SBS Brendrupp or best of all REBA but all of those will be getting close to 2 times the price of the extreme and maybe 3 times in the case of the REBA