Picked up an fc yesterday...big problem!!

[DubSeth]

I picked up an 86 rx7 gxl. It didnt start for 2 hours cuz it was flooded. the seller had a fuel pump killswitch so we would turn off the pump(to get the gas out of the engine he said) while cranking then flick it on...after a while it started. All was good till i got halfway home when it overheated hardcore and the overflow tank was bubbling and shooting water and the cap on the top left of the engine was shooting water...I had been running it at low rpms before that but someone told me today: "It's a rotary! u gotta keep the rpms high to keep it cool!"....idk if thats true but i didnt try it yet...I had already planned on getting an all new cooling system so its ok if i buy stuff. It was flooded bad so i think maybe some new spark plugs are in order because i couldnt pull the egi comp fuse(i think its called)....Any one have any help please?