Gen1 Gen2 Whats the difference I need to know!!

Hey guys my names Marty,
This summer i drove a 600hp 94' RX-7 twin turbo. It was the coolest car I've ever driven at my ripe old age of 18. Previously i owned a Mustang GT but now i see it has no comparison. Now im looking to buy a 7 but i cant figure out the differences. Obviously i want the Manual 1.3L rotary with twin turbo. I see some in my price range i think, but before i commit could u guys please tell me what im lookin for. The terms gen 1, gen 2, and gen 3 are like a foreign language to me. And from the looks of it, should i make sure a 7 at 80k miles as a new engine??? Please help define what the best RX-7 is because im eager to own one.

1st gen (SA/FB) 79-85. all non turbo, lightest rx7s
http://www.farmers-exchange.net/imagesAuctions/bartel/carSpring0579mazda041605.jpg

2nd gen (FC) 86-91 turbos and non turbos around. turbo cars had between 185 and 200hp
http://www.jimmys-rx7.co.uk/Images/White%20turbo%202%20G246.jpg

3rd gen (FD) 93-95, all twin turbo, 255 hp
http://www.ambassadorautosales.com/9371%201993%20mazda%20rx7%20pass%20angle.jpg

a 3rd gen will rape you on insurance since your 18
if your rx7 needs a new engine every 80k miles, its likely heavily modified