No there is no good way to find out what kind of cam is in the engine.
You cannget out the graph papper and degree wheel with dail indicator and make a map of the cam but it will still be pretty useless.
Lift and duration may help narrow down but factories made so many cams its next to impossible to say they never used one. Could be a car engine with big cam or tall gear heavy truck engine. In 78 a lot fo things were tried that didnt always work.
I would start by working the issues. Work the problem is a common statement at nasa cause of compexity trying to guess the cause is to hard you can only work the issues found back to a resolution.
Its in and it works dont remove the lifters or change the cam. Unless ypu are sure its the problem. With todays issues with cams wiping during start up i would take the safe road here with dad pickup.
Hope this helps.