If you are looking to improve the cockpit, both inside and out, for your 1/72 scale EMHAR F-3H Demon, I would direct your attention to this cockpit and canopy set from Pavla Models. Recommended for the EMHAR kit released in 1991, this set provides a new front end for the plane in detailed resin, which is a step above the old plastic detail provided in the kit. Modelers with some experience in using resin parts should have no issues with utilizing this set, and experience with vacuum-formed canopies will be very important if using the windscreen and canopy included in the set.
From my perspective, Pavla Models continues to quietly add new items to their product lines in order to add detail to existing kits; many of these lines are intended for aircraft modelers, but there are some AFV items as well. Pavla Models provides replacement canopies that are vacuum-formed as well as cockpit sets, ejection seats, and general detail sets for aircraft.