want to replace ignition with updated electronic one. What is everyones recomendations, Im in the US. been looking at VAPE or Rex Speed shop. Are there others I should consider.

I went with Rex's and it's been great. Several thousand miles and no problems. I believe it is was less expensive than the VAPE system as well.

I was in a similar quandary a few years before either of those systems became available. I bought a used DT250A/B/C magneto assembly from a member here, had DEET refurb that, and mounted it up. Had to manufacture a jumper to make the 'kill' switch function I think, but then found a repro 250A harness so got that as well. But.... the thing is still only 6 volts. Not a huge issue for me. I can understand how having the system be 12 volts would be desirable though, especially in traffic.

My question for the systems mentioned is about the battery, but I have heard from some they have found a SLA battery that apparently fits that small battery box.

I'd probably go with REX's, but I'm in NH and so are they. 

I went with Vape on my 76 DT400, great addition!