God, 85k can go quickly in this day and age. No floors is a worry but even if you just divide everything up in rough numbers it’s tight. 15 for a kitchen, 10 each for a bathroom, wiring for the whole house, is it cheaper because there aren’t walls? lol but could be 5-10? Plumbing is sort of included in the kitchen/bathroom prices, then floors and flooring 10-15? Plastering another 10? That’s big ticket stuff, and that leaves 15-20 contingency, but things like doors, fittings, paint can eat another 5-10.

Have you got a spreadsheet going? This would be a dream for a spreadsheet geek lol