I went to O'Reillys and bought a valvespring compressor like the first one you mentioned, it was fairly easy to use and only 20 bucks. I tried to rent one, but it wouldn't have worked on the valvesprings under the firewall.

 

Here's the one I used. https://ls1tech.com/forums/showthread.php?t=317675

Takes a little time to use but it does the job.