Looking to put a Jack Plate on my fish and ski please help

I currently have a Stratos 486sf with a Yamaha 150 four stroke on it. Looking to buy a Jack Plate and I spoke with Vance manufacturing and I wanted a six manual and they talked me into an 8-inch because of the way my transom is set up. Apparently Stratos and Triton have the kind of transoms where they taper in basically on the port and starboard side in the rear of my boat I sort of have Cadillac looking fins I'm sure I'm not explaining myself correctly so I'm going to post a picture of my type of boat. Anybody with Jack Plate experience please tell me am I better off with a 6-inch manual or the 8in manual thanks in advance

I have a ProCraft 215 Combo and was able to install a 5.5" hyd JP without change cables.

I think 6" is about the max you can generally add if you have stock mechanical cable steering.

The transom design features you refer to are really common now, because of heavier engines. Its sort of the opposite of the old Champions and Chargers that had the back corners cut off. Nowadays, heavier motors need the extra floats. They pop out of the water as soon as you get up on plane so it doesn't really affect your jackplate decision. I used a 6" Z-Lock, by the way.

typically fish and ski do better at 6 inch setbacks. any more isnt productive. i have a 6 and it worked out great

Thanks for the input does anyone out there think I need a low water pickup with a 6-inch jackplate or will my stock 150 Yamaha with the 20 inch shaft work fine

That will depend on how high you end up running your motor once you get the plate installed. I doubt you will need to run it high enough to need a low water pickup.

Maybe this is the wrong question but my Yamaha is a 20in driveshaft instead of the 25 you can still use a jack plate for the 20 or are they just meant for 25 in

yes 20 inch shaft is fine
. most boats on this forum are 20 shaft.
jackplate isnt to compensate for long shaft length but rather to offset weight and provided better leverage on transom and fine tune motor height and setback