New fresh new 440 build Lifter rattling noise. less than 1000 miles

My 440 been running awesome other than my bugs im working out, i started my car up this morning and i have a rattling noise coming from the lifters ( at least i hope it is sounds like it to me )
I warmed the car up its running fine but this rattle just started today. I am wondering if any of these can effect it?
I not started it in 3 days
The cold weather just hit its been down to single digits with high of 30 degrees outside

I checked the oil oil level is fine, The engine has about 800-900 miles on it so far so can lifters go bad that fast? they are stock ones I had put back on machine shop did all the work. or do they need tightened?
I hope they dont need tightened cause id have to pull the motor to do it the passenger side Valve covers cant come off cause the heater core box thing on the fire wall I barley fit the engine in there. the mopar valve covers said they were stock height but they lied they were about 1" taller than stock.

Is the car safe to drive with these rattling?
Author: 64Imperial