advice needed

[skeeter ss140]

I am currently running a 1998 115 V4 yamaha on my 1998 Skeeter SS140, I have added a hi-jacker jackplate with holeshot plate with 8 inches of setback, Hydrotec heads and my motor is extremely low hours and is 140lb on all 4 ,exhaust tuner, rejetted the carbs, had boyseen reeds put in, and while its a good running boat 61.3 with a light load turning a worked 23 pitch yamaha pro series at 6000rpms, I've always wanted more, I'm wanting to put a V6 on the back my boat is only rated for a 140 and I know all the disadvantages as far as insurance goes, I've had a set off SS 150 decals made for the boat and the boat is in excellent shape ,and I know it will handle more power, I'm wondering what V6 is the lightest so not to effect handling adversley, I like to put a vmax trp 150 on back that way I can use hydrotec part but I've also consideres switching to Merc power, I've heard that you can take a 135 2.0 merc drop on a 200hp powerhead change the tuner and have a 200 with 135 stickers and all, but I'm not sure can any of you guys give advice, I want to be in the mid to high 70s, my hull weighs right at 980lb and is 17'6ft. My boat looks like new, I've put a lot of time and money into it and want to keep it, thanks in advance for any advice also I'd be willing to do some trading for the right motor I need plus some cash of course no junk please,