Larry ,
I'd be very leery of the quality of aftermarket valves .
IMO most of the stuff being sold is made in china junk .
My choice would be GM NOS parts for your valve job .
These parts can still be purchased NOS .
You can go to ebay & type in the part # in the search box .
Intake Valves - GM part # 3688760
I see GM NOS inlet valves on ebay .
Dan's GM Obsolete
Chinook , Montana
phone : 406 - 357 - 2615
Dan's has ( 15 ) GM NOS intake valves in stock .
PIC
https://i.postimg.cc/HsF27qH1/Intake-Valves-GM-3688065.jpgThere are Exhaust Valves available on ebay .
Exhaust Valves - GM part # 3835318
PIC
https://i.postimg.cc/MHMB6GnM/3835318-exhaust-valves.jpgDan's GM Obsolete has ( 8 ) exhaust valves in stock
Intake Valve Guides
GM part # 3688760
There are some on ebay
PIC
https://i.postimg.cc/4y9KCF0p/Chev-216-Inlet-Valve-Guides-3688760.jpgExhaust Valve Guides
GM part # 3688761
PIC
https://i.postimg.cc/BnspJd0S/Exhaust-Valve-Guides-GM-3688761.jpgThere are some on ebay
Dan's has ( 18 ) exhaust valve guides in stock
Valve guide Seals
GM # 3835333
There are some nos seals on ebay
PIC
https://i.postimg.cc/HLnQxmPg/Valve-Seals-GM-NOS-3835333.jpgYou may want to consider new nos valve springs
They show up on ebay quite often .
PIC
https://i.postimg.cc/wTkJQMCz/Chevy-216-6-Cylinder-Valve-Springs-GM-NOS.jpg&
https://i.postimg.cc/Ls74v0gM/839304-216-valve-springs.jpgYou should check on the condition of the valve spring caps
GM part # 3835392
PIC
https://i.postimg.cc/6qX2dxzT/Valve-Spring-Caps-GM-NOS.jpgValve Stem Locks
IMO they should be replaced .
PIC
https://i.postimg.cc/FFV12qDg/Valve-Stem-Key-Locks-GM-NOS.jpgGeorge
'54 3600
