If you aren't looking to use too much cash then you should stick to the easy stuff that you could do yourself (without messing anything up).
I would suggest that you at least match the manifolds (both intake and exhaust) to the ports in the head.
A few things to know:
Never polish the intake ports (smoothing out casting flash is fine).
Exhaust ports can be polished.
You can grind the intake valve guide so that it is close to flush with the port roof in the intake ports but you should never grind the exhaust valve guides.
Don't go crazy and try to open up the ports as much as possible this will kill charge velocity and hurt performance.
3 angle valve cuts, when done properly, can help alot.
Other than that make sure all the valves seat properly and make sure the head is falt and clean and you should be fine.
Power, whether measured as HP, PS, or KW is what accelerates cars and gets it up to top speed. Power also determines how far you take a wall when you hit it
Engine torque is an illusion.