A question for the wise please.

Vehicle. 90/91 Vogue SE (says build date 90, but 91 on the compliance plate)
I have swapped out the ABS for a standard braking system from a donor vehicle. The brakes work great now, but I have a dash light problem which may or may not be related to the ABS removal. I never drove this vehice before as it was in a barn for years.
Problem 1. The handbrake when engaged, lights the transmission temp warning light, goes of when handbrake is off.
Problem 2. The Red, Left Centre, BRAKE (P)(!) light stays on. I believe this indicates problems with ABS pressure, fluid level, and also indicates handbrake engagement.

Is there anywhere that these two wires could be transposed? The handbrake switch has a black and white wire that goes into the loom and I have not tracked it from there. The temp sensor wires on the side of the transmission seem undisturbed. Is this a common problem with ABS removal?

I have pulled the main fuse from the ABS computer but have not removed the whole computer yet.

If I can't track this down I am thinking of swapping the wires at the back of the binnacle that go to the warning lights and go from there, but though I'd check on here first.

Thanks in advance.