kb3csw is right about rotating the engine with the plugs out. If the rods were already bent you would not feel anything.
Valves just would not open, or only open marginally.
45 minutes to an hour tops labor.
With plugs out remove valve cover, turn by hand and watch the rocker arm assembly and push rods.
Later...
While the cover is off you can also check you valve lash and verify oil is getting to the top end. When it is running.
You can run the engine with valve cover off.
I really doubt that you have any bent push rods. I have 6 old GMC L6 engines and only time I bent a push rod was when I lost the timing gear. Some timing gears are made of a pressed fiber material...others are aluminum.
You said this is a 1953 Truck...already converted to 12v.
GMCPic
Dance like no one is watching,
Sing like no one is listening,
Love like you've never been hurt.
1948 GMC FC101 1/2t Pickup w/270 and SM420
1948 GMC FC253 1t Factory 80"x9' Flatbed Dually
1948 Chevy COE 2 Ton 8'x15' Flatbed
1950 GMC 354-24 2 Ton 8'X12' Flatbed w/Dump Hoist
1953 GMC 454-30 3 Ton 8'x14' Flatbed w/Dump Hoist
1953 GMC 454-30 3 Ton Cab and Chassis
1942 Clarkator 6 MILL-44 Heavy Aircraft Tug
1942 Ford (9N) Moto Tug with 1/2 yard Loader
1947 Oliver OC3 HG-42 Tract-Crawler Bull Dozier w/6' Blade
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