Wondered if anyone knows of an electronic/hydraulic ssystem that can be bolted to the gearbox to change gears using bottons or padals on the steering wheel?

Pretty easy and commonly done with sequential (motorcycle style) gearboxes....

A bit more challenging with more common 'H' pattern type boxes...not sure it's been done or not, but I'm pretty certian it would be possible......maybe a case of whether it would be worth the effort or not...

There's the clutch to operate, unless it's a dog type clutch. Sequential boxes can be automated pretty easily because (I think) they don't have synchros.

I'd stick to getting the car running first, *then* develop the shifter...