Very nice jay welcome and congratulations on the classic looks lovley
Post up exact spec of car as is 300 bhp won't be cheap though
turbo upgrade vf series turbo or a Tdo5 or similar decat/sports cat exhaust upgrade bigger injectors better pannel filter/pod upgrade to newage top mount 3 port boost soliniod
But to be honest a good remap and sports cat/decat will have it driving very nice classics don't need massive power as they are so light
If it was me I'd do cat/remap/good tires disk pads braded lines and springs (some of which it might have already) and enjoy her
Hope that helps
Ciaran WRX