In leveling my frames to measure geometry, I've seen different top tube angle measurements depending on where I place the level, and as far as I know and can detect, these frames have not been crashed nor show an signs of crashing. Some have been aligned by a frames expert. I don't consider it a problem.

Side note, I don't know why a Tommasini fork would have less integrity than a Masi, Mondonico, early '80s Trek, or any other traditional steel fork. I think that having the builder's original geometry and aesthetics would trump, well, whatever makes you think they are inadequate. But, why do you think a Tommo fork might not be good enough?