Your suspension is fine with the spydershaft and I don't see what problem you would have with an aftermarket shifter.
I think the spydershaft has been tested at 500 rwhp on slicks. I don't how much than that it will handle though. Looks like your going to be making quite a bit of hp with that motor in your car if you go FI. You might want to look into how much power it will handle first.