RE: switching from a 3 speed to a 4 speed?
I am in a simular situation as you, but mine is an automatic. You can use most of what you already have, as far as clutch pedals and you won't need a 4-speed hump in your floorboard. The Keisler set up is nice and will improve your shifting and your overdrive. The trans will hold up to more HP and its a smoother shift. You can buy peices for your install and not have to buy the whole swap kit. It comes in pistol grip also and bolts in the stock location. I think the whole kit with hump, drive shaft and pedals, along with the trans and bellhousing is around $3000.Also cross member and associated wiring and speed o cable. You should look into this, it might be a better deal over the long run. Plus you will not need the whole kit and you could sell what you don't need as far as the 3-speed and such.