Strategy 500 tubes

[Whicker]

I have had my strategy for over 10 years and have never changed the tubes on it. I know this amp is a little rare but does anyone recommend some tubes? I know it has clearance issues for 6550/KT88 and 6L6 but I believe tung sol tubes seem to fit (thank you russia 35% tarifs...). But is there anything specific that people recommend, especially for the preamp tubes?

Thanks!