slixxor
Welcome to the forum.
As i see it your frame still requires some more welding, the base looks sound enough although we prefer some diagonal bracing, but the top rails are just hanging out there only supported @ either end, you really need a couple of stiffners to tie the top rail to the main structure.
I would personally go with epoxy leveling as you will get some more movement when you incorporate the bracing.
Regards
Mike