Quick update on this, it was abandoned until I sorted the brakes, which are now sorted (new servo fixed it!) so I'm going for the swap, I've decided to go for a swap to 110, seeing as it's a 110 loom and a 110 ecu! The only difference in the ecu is a couple of extra bits are turned on (boost control and map sensor) and slightly different maps, which doesn't matter, I'm remapping it anyway, and the only difference in the loom is an extra plug for the map sensor.
I made a small start on it today, I swapped the boost pipes from 90 to 110, no intercooler yet, I've just joined the two at the front, I have a large-ish FMIC that I'll be fitting when I get time.
I've taken the immobiliser off the new ecu to make the swap quicker, once it's up and running I'll pair it to the car properly. I've still got a bit of my christmas bonus left that I'll be spending on a timing belt kit for when I change the pump.
Only bits I need now (apart from the timing belt kit) are map sensor and in tank pump, which I think I have sorted thanks to this forum!