R65 or R80

I am going to get a second bike a 'doer upper'
Now that I am getting on in years a bit and started to work part time nowadays so going to get a project / hobby. Can't stand golf and definitely not taking up bowls, wife won't want me under her feet getting in the way, So I will confine myself to the garage.
Decided on a R65 or R80, I've had a couple of airheads (45,100) in the past, so I confident with these bikes.
Before I dive in and part with any of the hard earned.
Could I please have any indications of what to look for and what to avoid.

Go for the 80
Mono was the better handling but spoked/snowflake wheels seem to be more desirable ( heavy flywheel etc )
Start saving up...restoring one of these bikes isn't going to be cheap !

If you do end up going for a R65 get a later one, I think post '83 or '85 as they can take the 860cc big bore kits from Siebenrock which will turn it into a proper bike, rather than something a little under powered.

I really enjoyed my 65 (monoshock bike) it was good fun seamed to like being revved. Either will do you proud . Great bikes

As you will know, I have an R65 mono, but Mikeyboy made it nice.

Neither are performance bikes, only difference will be that the 650 will be revving a little faster to give the same performance as the 800.

The early 650s had better forks and brakes than the contemporary 800s, and in Oz are unloved and a lot cheaper.

860 kits are expensive, if you want 1000 cc performance just buy a 1000 cc bike.

Gearboxes , driveshafts and final drives are expensive to rebuild if badly worn so get the bike up on the centre stand and check for shake at the rim and backlash in the final drive, driveshaft and gearbox.
BMW recommend annual transmission oil changes so if the bike has been properly serviced all the transmission oils should be relatively clean, if you are able to check.

I will assume you know what a worn out motor sounds like -------------!

Replacement exhausts can be expensive , perhaps do a check to find out they cost, as a negotiating point if it needs replacing.
Bar switches are expensive too, as are wiring harnesses, starters and reg/regs not so much if you are happy with aftermarket kit.

I prefer spoke wheels, but the 800s with them are getting a little expensive----------.

A few hours browsing the Motobins, Motorworks, Siebenrock and EME sites might be beneficial as it will let you know a bit more about cost and availability before you get too deeply in!

Good luck.

^^That^^.

And dont pay too much money for it, whatever version you go for - a non runner, for example, is only worth non runner money despite what the owner may try and tell you.

These bikes have become popular amongst the hipster crowd in recent years so ahem "ambitious" asking prices for badly "customised" bikes is common. I would get an original example as possible.