Cockpit building from scratch

Hi Everyone,

I'd like to scratch build a twin engine helicopter cockpit that has a working overhead panel and over head throttles in fsx.
I don't know where to start. Any pointers would be appreciated.
I'm handy with engineering, and using microprocessors and electronics etc and have done a lot of direct X scenery work on fsx so am familiar with this app.

I don't want to have to program an entire aircraft type from scratch and would happily take something similar to what I need, and just adjust it.
For example, Dodosim have the stubs required for their Bell 206 Jet ranger that I could use quite well, and adjust the overhead throttles in my own interface, so that each
level adjusts the power by 50 per cent, so it seems like we have a twin engine helicopter instead of a single.
Problem with this approach is that the Jet Ranger does not have over head throttles etc. so that rules out that approach.

Any tips please, including the best way to interface loads of switches , hardware-wise into fsx.
I know there is project magenta and some kind of 'break out' board on the market.

Thanks in advance for anyone's kind help.