Depends on the individual and what you have available to you.
Good machine shops are always a question, and how much you want to spend could determine the outcome there. Waiting is always fun too
I usually save the machine shop building for numbers matching muscle cars where crate engines simply aren't an option.
If there is a crate engine out there however that fits your needs and originality isn't a concern, it's certainly a nice way to go.
If all you want is a vortec style gen 1 engine, instead of swapping in a 90's vintage 350 (that may need rebuilt anyway) I'd rebuild the one you have and install a set of vortec heads.
Only other difference with the newer block would be a 1 piece rear main and the ability to add GM style roller cam with the spyder setup rather than a retro fit kit for an older block. Neither of those additions are enough to persuade me to look for a newer block.