Sure looks like a thorough re-build!
Mine will need a re-build too in the not too distent future, however I'm under orders from my brother that his gets back on the road first, so I'm in keeping it going mode at the moment.
I have toyed with moderising to the Zetec, currently mine has a Fiat 2ltr twin, good engine but long in the tooth today and parts are getting rare and expensive. I have just swapped engines over, the previous one had a severe water leak through the head, and so to save time simply swapped like for like. A Chap called Mark Whiter had a modernnised Star which included a Zetec engine and aluminium side screens, fitted well and ran well too. Not sure where this car is now, it had gone to Holland.
I have no weather gear at the moment either, it had none when I bought it, I have since sourced a pair of side screens and will get a hood made in due time, we have the weather gear for my brothers so will use that as a pattern.
Regarding wheels, my axles are 4inch PCD and would highly recommend at getting 4inch wheels. If you are looking for a set of second hand one's then there are various vehicles with it, this page is helpful
http://www.vauxhallviva.com/?page_id=3125. In fact I have joined the Viva owners club. Having said that the alloys currently on mine which were fitted by the previous owner are 100mm which has resulted in the studs being bent inwards. I have new studs in readiness for the new wheels, but don't yet have the funds to purchase a set. If I remember correctly mine are 15x6 with a 25et.
Are you going to change the dashboard too?
Cheers
Mark