i think your car if it is in as good a condition as it looks should get you 1750 to 2k but its got to be what the buyer wants i would have it of you for a family runaround ,but with the mods and engine change i could see the insurance being tricky.
all cars are money pits jim, but i think you chose the wrong route when buying the saph if you spent 2.5k buying it and 4 on it think what you could have got cosworth wise for 6.5k. hard bullit to bite mate
stop trowing money at it mate,you know it makes no sence,you will end up with a cossie