I have to agree. Don't start unless you're serious. It would be minimum of 1 year for even the most talented fabricator to do something like this. More like 2 years though.
Me personally, I wouldn't bother cutting up an old beetle chassis and body, then welding back with all sorts of material (tubes, gussets, etc.). An old beetle chassis beefed up still wouldn't be as strong or handle as good as a body-drop on a Boxster chassis or similar.
https://youtu.be/lZDPuVhnhlY?t=311
https://www.youtube.com/watch?v=ka2qcp1JXwY&t=50s
https://www.youtube.com/watch?v=6jjZfISWfu0