Solid lifters are solid. There is no internal hyd lash mechanism.
Solid lifters allow the motor to rev higher because there is no hyd mechanism in the lifter to "PUMP UP"
and cause a loss of compression at high rpm like a hyd lifter can.
A cam designed for a solid lifter can have a more aggressive opening and closing ramp because it doesn't need to be as quiet as a hydraulic lifter cam.
Because of the small amount of valve lash on a solid lifter motor the motor will have a moderate mechanical solid lifter sound at idle.
When the lash is adjusted right the noise is not excessive.
Some "tight Lash" solid lifter street cams are actually very quiet.
The valve lash does not need to be adjusted every few weeks.
More like every 7000 miles.
I do mine about twice a year. takes me about 30 minutes.
All of Cheverolet's, Fords and Chrysler's highest horsepower performance motors of the 60 and 70's
had solid lifter cams.
To compare a solid lifter cam to a hyd cam you need to select a cam with 6 to 10deg more duration @.050"
because of the net effect of the valve lash.
A solid lifter cam will tend to have a little more low midrange torque, throttle response, and high rpm rev limit as compared to a hydraulic.
The more radical the cam and intended rpm, the more the advantage of a solid lifter. Especially beyond about 6200 rpm.
Comp Cams has a new series of Extreme Energy
tight lash solid lifter cams available from mild to radical.
Crane, Lunati, Isky and Sig Erson cams have simular
street high performance solid cams available.
A comparable solid cam to the Crane H278-2 Hyd cam
would have about 228to 235 deg @.050 intake duration.
A Comp XS-268S #12-676-4
or a Comp XS-274S #12-677-4
Would be a good comparable solid lifter alternative.
Two very responsive street cams for a moderate performance buildup.
Cranes smallest Catalog solid lifter cam is the PowerMax F278-2
A little more radical than the Crane H278-2
but a very responsive street high perf solid cam with good street manors.
Definately worth a look and consideration for your motor.
You can check out the specs here
http://www.cranecams.com/master/apps/chevy21.htm#1. PowerMax