Before I started having this work done on my 1968 Triumph Herald 1360 Estate. I was advised: You cannot repair the chassis properly with the tub in place. Potentially I could be opening up a can of worms. The same is applicable with you You wont know how big the can will be nor how big those worms are until you start and take it all apart.
Be prepared for supprises
Only one word is applicable COMMITMENT
Best of luck. Martin