If you do head portwork, you may as well go with the oversized valves as since you're already in for over a grand, the extra coin may as well go in. it does suck as you have like 300 for the valves and another 200 or so for the work.
headwork would be a good idea, nice gains available there, and it looks like you've already put some coin into parts. this shows the difference
between oversized vs not oversized valves. Back cut valves that are STD size though are pointless because at that point you should go oversized. Or you can reuse your stock valves, new springs/retainers, and cams with port work. Valves could be reused, and if you keep track of them should be fine. if not, or they hit the seats or something they can be re-lapped in and all is well.
You may also consider going with adjustable timing gears, but remember the bump on the intake cam gear is an issue for our cars.
Lots of other little things (IM, TB, coolant re-route, etc) but good luck.