Well, since nobody else has responded....
I haven't seen that kit in the flesh, but I may be able to offer a little. If I remember correctly, it was released in conjunction with several other 1/150 latter-day, steel-hulled sailing ships in the late seventies. I bought two of them, the Pamir and the Gorch Fock. Both of them were excellent kits - with a few reservations. The big problem with ships like that as modeling subjects is that the deck furniture is so complicated. I don't know much about the Amerigo Vespucci, but among the Pamir's most important equipment were Jarvis brace winches at the feet of all the masts. A Jarvis brace winch is almost impossible to represent realistically on such a small scale. Heller didn't do too badly with its Jarvis brace winches, but they're barely recognizable - simply because they're so small. (And if the model were on a bigger scale it would be extremely unpopular with Significant Others.)
The other problem I remember in the Pamir kit was that, as so often happened at Heller in those days, the designers didn't quite understand the subject matter - especially when it came to the spars and rigging. They made a gallant attempt to represent the jackstay eyebolts on the yards. (In reality jackstays are extremely small, but the model would look weird without them.) Heller represented the eyebolts with tiny, stepped rectangular blocks, to which the modeler was supposed to glue pieces of wire to represent the jackstays themselves. Not such a bad idea - but Heller put the "eyebolts" on the fronts of the yards. In reality, a big steel bark like that would have had two sets of jackstays on each yard, one on top, for the men to hang onto and for securing various blocks and other gear, and one 45 degrees to the front, for securing the head of the sail. The idea of drilling for wire eyebolts seems straightforward - until you remember that the Pamir had six yards each on three masts. With two sets of jackstays, and probably about twenty eyebolts for each. Do the math, and discover why so few models of that sort of ship get built.
My guess is that the Heller Amerigo Vespucci is a pretty good kit - maybe an outstanding one. But if somebody out there actually has one, for heaven's sake correct me.
Youth, talent, hard work, and enthusiasm are no match for old age and treachery.