87 Blazer w/4.3 swap *help*

i bought a s10 blazer about 4 months ago it originaly had a 2.8l when i bought it the truck would crank but not start what all should i look for to see if the swap was done right

only 3 things to make an engine run, (air, fuel and spark) the rest are components within the engine and it's assembly. if it cranks but does not start, go down the check list. #1 make sure you have fuel reaching the intake manifold (unhook the fuel line near the manifold and see if ur getting fuel) #2 spark....this could be a multitude of problems. first ensure your distributor is getting power w volt meter, check your firing order on your plug wires then check them again, this is one of the most common ignition problems. check plug gap, if it's too wide, you may not get spark with a stock ignition and you're engine will run hot. after that, i'd check and make sure the coil is good (common failure), timing, tdc the motor etc. 3# make sure your valve assmbly on the carb or intake isn't closed and air is getting in to the intake manifold.