Some initial thoughts, which may change as I ponder the question more!
Unless your 'in the business', when it's a source of employment and income (as well as hopefully enjoyment), golf is a leisure activity, something that ought to be fun.
Whilst my heart and soul would like to go back to some dim and distant yee olde period there are other factors to consider so that the game is more fun, or rather less no-fun. For example, playing in the cold and rain and wind in a soaking tweed jacket or a soggy jumper knitted by granny vrs playing in modern gore-tex or the equivalent.
With this scenario in mind I would be inclined to suggest some form of compromise, namely -
Clothing, footwear etc - near-modern period - but not so modern as at present when golf and fashion seem to be overlapping.
Golf ball - late 1990's era - Titleist Professional, Maxfli Revolution period - less distance than now and more workable but crucially (fun) still pretty durable in comparison to earlier periods.
Clubs - early 1990's - late steel shaft and wooden head period - more ease/consistency of manufacture but still with some element of uniqueness, more playable (fun) than previous periods but still requiring skill rather than strength, which seems to be how the modern game is.
Architecture & maintenance - still pondering this one - but courses would certainly be shorter and hazards more hazardous and all in an more open aspect style with less corridors of trees and with less ball hunting needed. Maintenance would be less manicured......they'd be some, but not to excess, sheep on the course (not greens) if circumstances/predators permit. Difficult not so be in favour of modern drainage and irrigation however, although not overused.
atb