1978 Subaru GF hardtop! now what?

so i stumbled upon a 78 gf hardtop in a farmers field, covered in moss,with no dents, very little rust,5pd, 41,000 mi. I tracked down the farmer and he said for 300 bucks i could have her. i had never seen one of these cars before. (i thought it was an old b210 at first) i towed it home and to my surprise had it running that day. now i drive it everywhere and love it! Still have yet to see another one and even the internet suggests that the car is a forgotten piece of the past. but now what do i do? mine is complete and everything works on it (lights, ac,switches, guages, everything!) i wouldnt say its a fast car but its not the gutless rolls/welk/anhardly that my old toyotas were neither. i would consider it "quick". Does anyone have any info on performance upgrades for the 1600? or ideas at all for a GF? im having a hard time finding any info or anyone who has one or any any other evidence (except a few pics on the internet) that i dont have one of the last ones left. they cant be that rare can they?