Son gets a 92 Civic Hatch for his daily drive

Hi, New to the forum and from QLD....picked up a pretty straight 92 Civic GL manual hatch reasonably cheap for my young son on the weekend with no roady.
It's got good straight panels, good white paint finish, no rust, Meshindo MS-578 mags with 16" low profile tyres, good gearbox and clutch, all electrics work.
On the downside the engine (D15B4) was running rich and blowing black smoke...spoke to a mechanic and he suggested that I try lubricating the linkages between the two carbs as they sometimes seize....seems to have worked a treat.
Changed the oil and filter as it was as black as tar.
Still has a tuning/timing problem (?) where it "hits the wall" and doesnt rev past about 3000 rpm under load...seems to idle and rev OK but not under load...read about all sorts of possible reasons for this from sensors,ecu to cat converter...might have to leave this one for the mechanic to sort out unless someone here has had the same issue with a D15B4 that I should check out?
Need to get a roady next week... would it pay me to change the plugs or am I best just leaving that for the mechanic to do as it will need a tune and other work anyways.
I'll post some pictures next week and let you know what the mechanic found out regarding the "rev brick wall".
Cheers

Civic is a nice car for new driver easy to drive and easy to maintenance. What you can do is to check the air filter in the black box behind the Dual carbies. Open the lid and see if the air filter is dirty or old. Try carbie cleaner to clean the dual carbie. Check if the Dizzy is working in good condtion. Tune up could help much. Oil, oil filter, spark plugs...
Also check the timing, http://ww2.justanswer.com/uploads/am...3_181135_1.gif
http://repairguide.autozone.com/znet...52800617db.gif
Good luck