Do all the reinforcing BEFORE you remove the roof! Yes, you'll need to reinforce the "B" pillar and that's going to take some engineering.

Don't forget: Reinforcements front to rear underneath are one part of it. You'll need to reinforce the body inside side to side as well. This can be done inside behind the back seat (or in the trunk) and just inside the hood. This will be necessary to keep the windshield from shaking and to make it drive without flex side to side.

If you're going to do an actual cabriolet top, you'll need to narrow the rear seat back to allow the folding top to clear in the down position.

__________________
1968 230S Automatic, Elfenbein
1975 O309D Executive Westfalia Camper Bus, Blau/ Weiss
1972 280SEL 4,5 Dunkelrot
1966 VW Type 34 "Grosser" Karmann-Ghia
1963 VW 1500 Variant Pearlweiss
1969 VW Variant Automatic, Perugruen
1971 VW Squareback Automatic, Clementine Orange
2001 E320 4Matic Wagon- Our belated welcome to the 21st century! Polar White
1973 280SEL 4,5 Sliding Roof "The Bomb", Dunkelblau.