An engine with a solid lifter cam needs to be installed in a vehicle with acetyline headlights, mechanical brakes, and a hand crank. All those items are the same degree of obsolete. Yes, solid lifters need to be adjusted periodically- - - - -maybe every 10K miles or so. Once they get slightly out of adjustment, you'll either get burned valves (too tight) or battered rocker arm tips and valve stems (too loose). A good set of hydraulic lifters, adjusted properly, should last 100K miles or more without any further attention. The old wives' tale about solid lifter engines performing better is also a myth- - - -I've gotten 600+ HP and 7K+ RPM on the dyno out of hydraulic lifter engines.
Jerry