My motors are 1994 merc 7.4L carb big blocks. What are some of the best spark plugs, oil filters,oil.

ttt

Its all a matter of opinion.

I run NGK plugs, and Mobil 1 syn oil and a Mobil 1 oil filter.

i run ngk and valvoline racing oil with delco filters

Merc recommends AC MR43T spark plugs and Mercury 25W40 oil. You would safe to use that.

I use NGK V-Groove plugs, Valvoline 40w Racing oil and a Wix Racing oil filter.
I do believe your engine came with AC Delco plugs ( MR43T ). Those are good. You can have a parts store cross that number over to your brand of choice or I will do it for you ( I manage an auto parts store ). Send me a PM and I will give you all the part numbers for the parts you need.
Donnie