Slow progress......
Decided to go with a paint stripper, primer, wrinkle coat combo, not 100% perfect, but a big improvement on what was there.
Hoping to reassemble this weekend, just waiting on a new set of fuel injector plug clips. I managed to drop / lose one somewhere so might as well replace the lot.
I'm also on the hunt for an engine bay firewall panel (the piece that sits against the firewall between the two cabin filter boxes) in reasonable condition, part number in photo below. Mine has gone brittle and nasty. I see them on ebay etc. but they are an odd shape and shipping is crazy, plus would rather buy local where possible.