The 059 and 520 heads flow very similarly, increasing all the way to 0.500" lift. Can use the same Comp 787 retainer, 0.050" offset locks and LS beehive combination as the L31 head to gain lift capacity.
For a shelf cam, I would probably go with a Lingenfelter 74211 in that truck. It is the 2nd lightest truck that engine came in, you have a looser converter and decent gearing. Keep in mind if you go with those wheels, you will loose a lot of what the engine modifications will gain you from the additional rotating weight. I am not a huge fan of a dual pattern cam in a 305, but not many single patterns exist that are EFI friendly in a 305 without a lot of tuning. The 74211 has a 211/219 @ 0.050 duration and it is on a 112 LSA. It will still make decent vacuum to keep your power brakes happy. With 20* more duration at 0.050" on the intake lobe, it will move the powerband up a fair bit but given your S10 converter should stall about 2,400 rpm behind a L30 if it is running well, it will jump right into the powerband quickly. The GM ZZ4 cam is also a very similar grind at 208/221 @ 0.050 on a 112 LSA and probably could not tell a difference between the two from the driver seat. The Summit 8801 is also right there in the mix spec wise and some seem to love those Summit branded cams. On paper it should also be right there, but no first hand experience with that grind, unlike the other two.
In a 305 using a generic shelf cam (almost all are spec'd for a 350) I would get a Cloyes 9-1157 single roller chain with the 3 way adjustable crank sproket and advance the cam 4* with a cam of that size. 305 needs to close the intake valve a bit sooner than a 350 to keep its low-speed torque, but needs a fair chunk of duration to get decent flow through its smaller intake valves and smaller bores, letting it breathe to make power. Given a 305 and 350 have the same size exhaust ports and exhaust valves but exhausting a smaller cylinder, the 305 does not benifit as much if at all from the larger split pattern grinds often ground for the 350 that favor a substantially larger exhaust lobe in duration and lift.
Almost anything generic off the shelf is not ideal for anything other than a basic 350. You might call the guys at Clay Smith or Lloyd Elliot at Elliot Port Works. Even though I eventually went with a Lloyd Elliot specd Erson cam to replace the flop that Comp Cams specd for my 383, I talked the Clay Smith guys and they were right on the money. I liked the specs on the Erson that Lloyd and I collaberated on just a bit better, so it ultimately won out.
