Absolutely ..
If your going to have everything (engines , tanks etc) out of the boat then by all means flip it !
I've done both of mine and the cost of getting a knowledgeable skilled crane operator to roll it over and then back upright is worth every penny !
Certainly fair , sand , and prime everything while it's upside down but if you can finish the hull bottom once and for all then DO IT ! You'll more than likely never have it inverted again .. Unless you're a really unlucky driver