Change Cam - Gain 77 HP ..... "article on page 22, in the magazine" [Best of Tech /Winter 2003]
A few years ago there were claims by a magazine of adding 77 horsepower to a wimpy 8.6:1 compressioned 355 sbc equipped w/"the usual hot rodding parts" headers, 750 Speed Demon carb, Edelbrock Performer RPM Air-Gap intake, 2.02/1.60 Summit aluminum heads, MSD, ect.
Just using an Erson TQ40 cam kit [218/228@.050 duration][.472 valve lift, w/1.5:1 rockers]
instead of the stock small block Chevy [195/202 duration] factory type [.390/.410 lift] camshaft ...
Using this Erson TQ40 cam, it showed gaining a maximum of 77 hp @ 5,600 RPM = [403 hp/maximum] .....
and gaining 20 pounds of torque, @ 4,400 RPM = [418# torque/maximum] over the stock low lift camshaft.
Oddly enough, from 2,000-to-3,900 RPM, results were [-1 horsepower] and [-4 pounds of torque].
Average gains from 2,000-to-5,900 RPM, were 44 horsepower & 35 pounds of torque .....
This Erson TQ40 cam showed gaining 78 hp & 78 pounds of torque, from about 4,000-to-5,900 RPM.
.....Read that part carefully.
Oddly enough, from 2,000-to-3,900 RPM, results were [-1 horsepower] and [-4 pounds of torque].
A TQ40 cam would be a TERRIBLE choice for a heavy El Camino, stock converter, 3.36 gears. Think about it,
... on the street and during a 1/4 mile pass, that car will spend a LOT of time in the 2000-3900 rpm range.
If ALL torque gains are above that RPM range, any real performance improvement will be minimal, and the car won't feel much stronger SOTP when screwing around on the street.
You want to keep the duration much smaller IMO (< 215 @ 0.050).
Isky 262 Supercam or 264 Megacam would be a good choice ....
Re: Mild "budget" 350 cam ... suggestions
Get a Crane 274H06 or Isky Mega 270. It will give a lopey idle without totally killing performance, assuming you only have stock 76cc heads and dished or flat-top pistons (8:1-9:1 CR).
Honestly, even those are a bit big for that low CR, but much better than the ones you picked above.