the first step in an a series cam swap is remove engine from car,so i hope you've done that.put the engine into a stand,turn it upside down,remove the sump,then let gravity hold the lifters clear while you put the cam in.also, always put some form of lubricant on the cam
& bottom of the lifters,this can be anything from a good quality engine oil to special moly
cam lube.the idea is to stop the cam lobes wearing on the initial start up.i've always used
cam lube & most auto stores will have something to do the job.don't be afraid to use lots,either.as a good friend of mine always said,
'oil is cheaper than metal'.