Valves, guides and springs, LM2.

[Stevex]

So, the old girls coming up to her 40th birthday and I've no reason to believe the cylinder heads have ever been touched. The bike has approx 36K miles on open bell mouths and I'm thinking next winter about replacing valves, guides and springs. Is it a fair assumption to consider this a vital issue?
I've done a lot of work in Guzzis but never replaced these items, so how difficult a job is it and should I consider giving it to a machine shop instead. Will the seats need re cutting? How much reaming of the guides is usually required? Do the springs need shimming and if so, how? Anything I've not considered?
Thanks.

[Don G]

Take your heads to a reputable repair facility, supply them with specs. and parts as needed.  DonG

[moto-uno]

  Don't consider replacing the guides yourself unless you can guarentee that you've removed every last bit of carbon from them .
Even then I drill them completely off until I get to the head surface (from the port side) . Reaming them is probably a machine shop
job , as it cutting the seats ( which you'll have to do if the guides are replaced ). And if you're only doing this every 40 years , maybe
just follow the above suggestion  . Peter