The Amco tops are high quality, if you have one that is in good condition but is too small it can be stretched.
If it tears during the stretching then it was probably too old and dried out to be useful. (or the stretching was too vigorous)
When stretching it do it a bit at a time.
My bows have the retracting springs so they can be made a little shorter.
I hooked the top on the back and over the rollbar without the bows in place then I pulled it to the front and stretched it to attach.
I left it like that for a while (24 hours) then pulled it off the front and put in the bow in it's lower position.
I had to pull pretty hard to get it to hook on the front studs, I didn't bother with the bar. Left it that way for a while then opened the releases on the bow so it applied more pressure.
After another day I tried hooking the front bar around the lip of the wind screen frame, this took some work but I finally got it with the bow in the lower position, then again I released the bows to apply more pressure and stretch it a bit more.
I haven't removed it since, this has been a few months.
It's a heavy duty top and I'm really glad I have it and made it fit.