When you say it's in great working condition, does that mean it's been recently serviced? Make sure its springs and grommets have been replaced, hopefully during this century. And make sure the original bearing is in good shape.
I'm not familiar with an Audiomods Classic tonearm. Maybe someone else can chime in.
As you know, if you're open to the idea of upgrades, you can use a 1978 LP12 as a platform and upgrade it into a dizzying array of later iterations. Linn has used the same LP12 base for all of its upgrades since the table was introduced in 1974. The money for Linn's latest upgrades is ridiculously high, but you should be able to find on the used market, say, a Linn Ittok tonearm, a Cirkus subplatter, and a Lingo outboard power supply, and then you'd have a quite nice turntable. I don't know current prices for these upgrades, but if you bought the 1978 turntable for, I don't know, $1000 and got all the upgrades for, again, I don't know, $2000, that would money well spent, IMO. Spending more than that might not make sense, given how many good turntables there are these days for $3000-$5000.
I have a 1981 LP12 will the Cirkus upgrade, an Ekos tonearm and the Lingo (version 2). It's all the turntable I need. I've had it since 1996 and it's not fiddly at all. The legend of the finicky LP12 is, at least in my experience, blown way out of proportion. Mine is on a shelf mounted to a wall, and that takes care of the bouncy suspension getting out of hand. I had the springs and grommets replaced when I got the Cirkus mod 20 or so years ago, and I've yet to need to fiddle with them.
