Red and ND filters on bay 50 Zeiss planar

bear with me. I've been searching the internets for the best answer here. As a black and white (and frequently, weather) photographer, I'd like to use these two filter types (actually, circular polarizer, too) on a 1975 80mm planar bay 50. Is the best option here scouring eBay, etc. for original 'blad filters, or is there an adapter with a very close OD to the lens that won't interfere with an original metal 80 c lens hood?

Thank you as always for your time.

Adapters surely exist, (i am not familiar with them) but as you mention they might interfere with the hood.
I think B50 filters are the best way to go. They should go for about $50 (give or take) at most. Ebay is an option if you are in a hurry. If not, you can visit photo stores which carry second hand items, many have boxes full of old filters. In my experience you can get good prices this way. FYI I found a B60 polarizer and some others for $29, uv filter for $10, etc this way. Good luck with your search!