For the cam -yes, it will be alot easier with the engine out of the car, because to do it with the engine in you will have to take two motor mounts off, jack up the passenger side of the engine enough to slide the cam out over the fender.
Another cheap, easy mod is a 3.4 or 3.5" pulley (you'll have to check into www.clubgp.com
and find someone with a pulley-puller). If you only are going to do it once I suggest a press-fit pulley, and not a modular pulley as they are 3-4 x as expensive.
A cold air intake or bumper well intake (need to order 3.5" tubing from www.Intense-racing.com
), a high flow 2.5" catalytic convertor (part # 94106) from www.justmagnaflow.com
($55.57 includes free shipping), a better muffler (same place -get part #12265 with single 2.5" inlet and dual 2.5" outlets -$84.22 -free shipping), and a 180* thermostat.
You might also want to port your exhaust manifolds. There is a guy that Sol had do his, and the guy did it for $100 + shipping (you will need to supply the cores -note: the rear manifold is different on the Bonneville than other body styles). I have the guys e-mail address if you are interested.