That would be a starting point and depend on the body and weight carried. Can you ask the conversion company (if it still exists) for its recommended values?
'69 Mk1 V4 >> '76 Mk1 V4 >> '84 Mk2 OHC >> '97 Mk5 Banana >> '09 Mk7 TDCi The van in front is a Transit. It might be my Mk7 - follow the trail of rusty water:Diary of an Ordinary Van