Rear subframe cont'd

I've cut the square down tubes of the xr650 rear sub frame, and used new aluminum tubing which are drilled and fixed to the mainframe square section. I will strengthen the holes with some drilled bar and insert into the ends of the tubing. One side is attached as a mock up, I'll do the same with the other side. Fixed using stainless bolts but may change for alloy. Fixing the seat would mean a small bracket would have to be crafted but bolted to both, that it the easy bit, the hard bit will be finding a small enough battery. If I have a total loss system ill need a battery which will last a race just to power the rev counter, ignition cdi and coils. I was thinking of using a mobility scooter battery as I've seen some rated at 20 amps but look quite compact. The battery will either go under the seat at the back or somewhere down below hidden in the fairing which is another job to do. When the seat unit is fixed in the right position then ill go round re-welding and strengthening at the moment it's all tacked on in places.