Do you want to keep it manual? Or automatic is okay?
5.7 Vortec/4L80e swap would be a natural swap for automatic. A 10k budget you can upgrade to a 383.
You can also do the LS swap if you'd like. Do a search on here. Lots and lots of threads.
Are you doing the work yourself?
Have you researched the smog rules in your area? I hear they are strict, not sure if statewide or just big metro areas.
But if an engine swap is a pain in the neck with state officials, spend 8k to move out of the state, then 2k for any junkyard V8 will get you the same thing. Just kidding on that one.
Or just keep the old Chebby for when you need to move a fridge or couch. I like the idea of getting something that was actually "meant" to be fast by engineers and designers. I'm pretty sure even a stock, late 90s F-body with an LS1 would blow the doors off a souped up N.A., heavy RCSB truck, unless you do some NOS, turbo or supercharger.
F-body: Cheaper, better, lighter, more aerodynamic, faster, less headaches, no downtime, etc. Just pay seller, fill with gas and put smiles on your face. I see some of those cars around here for way less than $10k.