ALL '87-up 4.3 blocks have that 4.3LG cast in there, it means it's a 4.3. Look at any '87-up 305 block, it'll have 5.0LG there, 350s have 5.7LG there.
If it's a vortec, there will be an electrical thing in the timing cover, at the bottom, slightly to the passenger side.
Vortec 4.3s had 2 different cams, the difference is 10 horsepower. They're commonly referred to as the 200-horse cam, and the 190-horse cam, although the smaller cam version has been rated as low as 180 horses in some apps, mainly due to the exhaust systems.
IDK about '07-up, but for '96-'06, a Vortec 4.3 is a Vortec 4.3.
for headers, try Edelbrock first, then Hooker, then Hedman. All offer different versions, with Edelbrock having the most versions, by far.
There are underdrive crank pulleys, TB spacers, and even special rocker studs in case you want to convert to 1.6:1 rockers. COMP offers some specific cams, and there's always porting and polishing for the heads and intake. Plenty of performance mods for these engines.