Dave - here's what I found searching GM Partswiki in the screenshot below reference your intake valve # 2193984. It lists your number as fitting 1955 (Y code) 302's and there is another 302 intake valve # 2304149 that fits 1956-59 302's (STX codes). Not sure if that might be a suitable replacement for your valve needs or not?

I did find that the "round horse shoe keeper" you are missing is listed as GM# 2192706. You can acquire a replacement (or more) from Olds Obsolete as they show having some in stock. Picture of that piece also below.

Hope ths might be of some help.
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~ Dan
1951 Chevy 3 window 3100
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"My Grandpa Carl's Truck and How it Became Mine"
1966 Chevelle (Wife's Hot Rod) | 2013 Chevy Silverado (Current daily driver)
US Army MSG Retired (1977-1998) | Com Fac Maint Lead Tech Retired (1998-2021)