SCT X4 question and crank relearn advice wanted.

Hi guys,

I've just installed a 2014 engine into my 2011 GT and I think my ECU has a tune on it, only worked it out when it would only run with a big JLT intake and wont run with a stock one. I want to retune the ECU to a tune that I know and trust. Now with that, can I just flash the ECU straight onto a new tune? Or am I meant to return to stock first? Because I can't actually return to stock as my ECU is already tuned and I'm from the UK so getting a stock tune is quite difficult without sending my whole ECU off to the US.

So basically, can I flash and already tuned ECU onto another tune with the X4 without returning to stock first?

Now I'm also having issues relearning the crank sensors. Nothing seems to work. We've tried revving it higher, taking it for a test drive, still not working. Any ideas or tips on how to get the damn crank sensors to relearn? The garage thought it might be the unknown tune that is currently on the ECU but I'm not so sure. Also the engine is working fine other than not crank relearning properly, is it still safe to drive? Because as far as I'm aware the crank sensors only identify misfires, but I'm sure I will be able to tell if the engine is misfiring anyway.

Thanks!