I agree with Dude and Kip. But since you asked, the only real issues are getting the chain/cams/crank in the right position and adjusting the pre-load in the hydraulic elements of the ball studs. I assume they know how to torque the heads, clean the gasket surfaces, etc.
But if you pay for anything more than the original repair you are getting royally screwed.
Falls Church VA
'66 200, '66 230SL, '96 SL500. Sold: '81 380SL, '86 300E, '72 250C, '95 C220, 3 '84 280SL's '90 420SEL, '72 280SE, '73 280C, '78 280SE, '70 280SL, '77 450SL, '85 380SL, '87 560SL, '85 380SL, '72 350SL, '96 S500 Coupe