Stop Fuel Leak

Ima guessing It's leaking around the filler-pipe?The new seals the tank manufacturer sends along, seldom work.
If possible reuse the old one,but clean the filler pipe first.The pipe needs to be rust free,and smooth,from the lower-most end to the sealing area and about an inch higher. Further, the used seal most also be oxidation free,at both sealing surfaces;inner and outer. Silicon grease is the best lube I have found,to help the pipe slide in.

As alluded to,the rubber sealing washer at the sender,requires a good amount of pressure from the pressure ring,to prevent leakage. Again reuse the old parts if they are serviceable; both the rubber and the metal ring. They are kindof a matched set.

You're gonna need a lot more tire.A LOT,more! heehee. 245s are just barely adequate for the front, but they are really hard to fit there on 15s. 275/60s are just barely adequate for the rear. As it is; stay off the gas around corners in first gear at least!If it bang-shifts in the turn, and breaks loose,you could be cutting a donut; surprise!If you are really on it, you will be up on the curb in a hurry.As other motorists around you, passing by, give you all kinds of hand signals.....Very embarrassing.
Oh wait that was me :(