I would have made the seat an interlock. I have done many seat mods. Perfected it. The only part of the j seat you neat is around the tank and where it locks to frame. You are basically making the letter "I" with the j seat. : explanation ::: MIND YOU THIS "I" IS ONE PIECE...only use enough of the front of the j to go around the tank ( this is the top part of the "I an. The center of the "I" WILL EXTEND CENTER OF THE TOP PART OF THE "I" BUT ONLY TO BE WIDE ENOUGH TO EXTEND AN INCH OR SO OF EITHER SIDE OF THE SEAT LOCK AND ONLY A FEW INCHES PAST IT LONG WAYS. WHICH IS WHERE THE BOTTOM OF THE "I" IS. THE BOTTOM PART OF THE "I" WILL ONLY BE AN 11/2" ON EACH SIDE WIDER THEN THE MIDDLE WITH THAT SAME 1 1/2" TO 90 UP. THERE FOR WILL HAVE ROUGHLY A 5" X 1 1/2RECTANGLE AS THE BOTTOM OF THE "I" AND NOW YOU CAN USE THIS PIECE TO MAKE AN EXACT TRIM INTO THE B SEAT. EXCEPT!!!... YOU WANT TO SAVE OFF SOME OF THE BOTTOM OF THE "I" EXCEPT FOR THE LOCKING SECTION AND LEAVE ON THE B SEAT THE SAME HIGHT YOU SHAVED OF THE THE J. NO THE "I" J SEAT WILL FIT INTO THE B SNUG AND SIT ON THE B SEAT LIKE A INTERLOCKING TREY. I USE A BRIDGEPORT. BUT. AS LONG AS YOU TAKE YOUR TIME AND BE ACCURATE YOU STRAIT. THEN YOUR CAN PLASTIC WELD' FIBERGLASS' ' TO YOUR HEARTS DESIRE. TOTAL SUPPORT BECAUSE 85% OF THE B SEAT IS USED ON 3 OF 4 SIDES WHILE SUPPORTING THE J "I" and lock from bottom. I personally use marine epoxy. Mixed with high psi epoxy. Light weight 50/50 with extra hardener. 10x stronger than and plastic weld or fiberglass.