Well getting a machine shop to port a cheapy cast iron head is not very cost effective. Machine shop hourly labout is expensive.
You can actually finish them yourself. You'll need basicaly 1 carbide cutter 3/8" diameter cylinder shaped with a rounded end on a long 6" shaft.
you can completly contour the guide boss using this one cutter on both the intake and exhaust port. you need this long shaft cutter to get deep in the intake port from the manifold side.
The worst that can happen is you touch the valve seats with the die grinder cullet or cutter and need the valve job touched up.
You're not trying to make a prostock head outof them but a thourough complete porting is nessessary to make any power with these heads.
the port walls are nice and thick and will take a good porting.
Buy this book
the S/R heads are covered specificly, in it plus a lot more.
You can also search my old post on porting 305 heads. The job is the same.
Yes you can buy all the rear end traction stuff from Summit racing. Its pretty straight forward. You need to modify the rear axle control arm geometry to eliminate axle squat and increase bite. The air bags do a good job of equalizing the right/left wheel traction making the LS differential work all the better.
The lower control arm relocation brackets and stiff lower control arms with stiff poly bushings are key . The adjustable upper control arms allow you to adjust the rear pinion angle. Once set up right the car will really hook up with a sticky tire. A drive shaft loop is recomended.
Can't help you with dialing in the Edelbrock EFI, I;m a old carb guy.
The bolt on track bars don't do much more than bind the suspension on these cars. Keep the sway bars.