Question on repowering 1990 200 Striper

[Aquamaniac]

Have been reading through all the threads on repowering (search is my friend) but haven't run into clear info applicable to my situation. 
So.....anyone have thoughts on swapping my ancient Frankenmerc 150 (378#) to a Yamaha 150 four stroke (467#) on my '90 200 Striper????
At present, have three batteries in console, a MK bow mount TM, and two anchors in very front hatch. With wife at helm and me standing in stern to check....the scuppers are above waterline.
The extra 90# is concerning. Guess even if it would work, it would preclude adding a CMC PL65 jack plate. Only 5-1/2" setback and about 30# more.....but the shift in COG I suspect will be the proverbial straw.
In any case, please share your thoughts!! Thanks.
BTW....hope to get input SOON.....going to look at a DEAL on the Yamaha F150 today!

[RickK]

The only true way to tell is stack 90 lbs worth of sand bags on top of the existing motor and step in the back and see what happens.  Otherwise we'd just be speculating.