hrm, i'd say timing adjuster and pullies. unless you plan on getting a chip sometime, then skip on the timing adjuster because you can bump the timing up with the chip. gears....definitly 4.10!!!

they are awesome, we put em in our saleen and wow. i really wanna put them in my car now, heh. you could also go with a shifter as well, i have a pro5.0 in mine, others have tri-ax. it's pretty much your pick, everyone likes both.
shifter
pullies
timing adjuster (if no chip)
gears (4.10s)