Nice, but you shouldn't make the Cubans attack Tommy, because he's their ally.
I have an idea, I call it "Hidden Assassin", inspired by HippieCommunist's Gang Wars SCM mod for III:
"A hitman will be roaming about on foot everywhere in Vice City, looking for Tommy, his model will be always random, making him look like any other male ped.
If he sees Tommy, he'll attack him after waiting for a while (target confirmation).
At night time, he'll slowly start zeroing in on your current position if you stay in one area for a long time.
He will start appearing when Tommy receives a phone call where Sonny tells him "I ain't forgotten about you", or you can use a separate CLEO script to make him appear always."
What do you say?