First of all, it’s looking great! Keep sharing the progress!
Secondly, there are 5 bolt chainrings available for purchase. I can’t see any details of the crankset in the picture, but it looks like a square taper crankset with a larger 5 bolt pattern, maybe a 110 BCD.
You can pick up a takeoff 4 bolt 104 BCD Shimano Hollowtech crankset on eBay for super cheap. I think your BB is a 68mm, so it shouldn’t be an issue in regards to fitment and you could probably get a whole setup for less than the cost of the chainrings on the vintage set.
The last crankset/BB I bought on eBay cost me $25.
It is definitely 5 bolt with square taper. After inspecting it more closely it looks like some of the teeth are worn down a bit so I will start the search on ebay. I had ordered a Shimano UN55 BB to replace the current BB. Will I need a different one for the Hollow Tech? I’m starting to get the hang of how bikes are put together but still a noob. I’m used to pulling apart cars.
You can see the difference in the wear on the teeth below:
