I partially restored/modded/improved a 1967 Split Screen Bus, read money pit!
Also Golf GTI mk2, 16v mk2, G60 mk2 I could go on.
Even the G60 which was one of the lowest mileage (if not the!) cars in the country was a severe leach on your finances!
Several times at VW I was told that the spares they had just handed over were the last in Europe!
Here is another example: The 16V needed a new exhaust so I decided to do it myself as generic exhaust supplier wanted silly money to fit new exhaust and it was cheap at GSF. I soon found out why! It was impossible to fit the front section without dropping the subframe and the previous guy had just cut out the old one and fitted an 8V version with no resonator ( I was trying to make it factory original) because of that very reason! It is a real heart breaker sometimes and after lots of years of battling rust and silly things TBH I sold up.
Whatever you budget, double it at least!
This is also correct for restoring as you will become very friendly with car specialists:
I need your bank account details!
Try to get to the VW show at Stanford Hall its the best and will give you a very good example of whats involved with a mk1.
Have a chat with some people and get some names and web addresses it will mak things easier.