The basic 240sx swap?

hey whats up i have a stock 93 240sx coupe and my ka24de been having problems. i've done a oil change,new spark plugs and wires,and had a problems with my fuel injector and when i have it on full throttle it doesnt pick up power at all.Plus the timing chain is hitting the valve cover and clutch slips because the previous owner didnt take care of the car that much left me with probs. So would it be worth to fix all this and add little bolt ons or go for a sr20 redtop and add a few bolt ons so i can get over 250 with stock internals so i have a motor i can learn better with b4 i do a bigger swap and drop a 2jz in my 240. So can anyone give me some ideas or which is better