Unfortunately the paint didn’t stick to the head and flaked off. I jetwashed the paint off re-painted, using etch primer this time.
Whilst waiting for it to dry, I tackled the waterpump. Immediately, I had an issue where the inlet seemed to foul the block. I wasn’t sure if I was torqueing the pump against the face of the block or against the inlet flange/block.
I checked the pump on the original engine (that I was just going to re-use), and this had a relief cut out in that area.
I checked the original waterpump from the mk2.5 engine and this had the same relief. That was (presumably) a genuine Mazda waterpump, but the one I fitted to the mk1 engine was aftermarket. This one without the relief was also aftermarket, so I presume they hadn’t bothered with the relief to save on costs. Maybe it is ok, but I’m not happy with it so am returning it.
I picked up a replacement from my local motor factors and it was fine.