[tech] similarities b/w 7a & 3b

[Jonas K.]

Ok, so after owning my CQ for 2 months I've decided that it thoroughly needs
positive manifold pressure. 

I'd like to stick with 20 valves, which makes it an expensive proposition. 

But my brain has been cranking the gears, and I'd like to bounce a couple of
thoughts off of those that might know. 

Does the 7A and 3B have the same bore? (i.e. could I use 3b pistons in my 7a
motor to get the correct CR. this assumes the heads are identical)

How similar is the 7A brains to the 3B. I'm hoping that the wiring is the same
and that the box will plug into the old harness. Odds are they're different, but
I'd like to know. 

My simple thoughts are that I'll pop off the head, swap in some new pistons and
put the head back on. Then attach all the external engine pieces needed for a
turbo and convert over to 3b ECU, and I'm good to go. 

I figure what I need is:

3b pistons
3b (or RS2) exhaust manifold
turbo
3b (or custom) downpipe
3b intake
3b ECU (wiring)
plumbing/IC. 
Do I need a tie rod too?
what about injectors?

This is the initial planning part and project is at least a year away from being
executed, if at all. 

Thanks for any input, 
Jonas 
90 CQ