Head gasket fit up V6

It's usually the manifold seal that leaks, are you sure its not running down from there?

You forgot about "Murphy" haven't you ?!..............first of all NEVER assume "they" m/c your block and heads
"true flat". Once you have a known & proven "Straight Edge" the length of your 3 pots at a diagonal, test all 4 surfaces at their 'diagonals' as well as their 'straights' with feeler gauges to establish how good a job was done.
Like painting.........preparation, cleanliness and testing is the basis of a good job welldone.......tedious and long-winded as it may be..............Did you double-check ALL holes in BOTH Gaskets against BOTH heads to ensure 100% correct gaskets ? ........Did you test your Thermostat on the Kitchen stove regardless of its age, and does it have a 'relief hole' of around 1 mm to allow "air bleed", before install to engine ? .......Did you follow Gasket Manufacturers advice re fitment ? ..........If no instructions, or questionable quality of H/Gaskets, then a light spray of "Hylomar" on heads and Block just before INSTALL, can be of huge benefit............
......NOTE.....ALL ABOVE IS ASSUMING YOU'VE PROVEN YOUR LEAKS really are AT THE HEAD GASKETS
Never be in a "hurry" like the guy who.............
"Never Has Time To Do the Job Properly the First Time, 
but Then Finds The Time to do it Properly the Second Time !"
 
Good Hunting
 

Inlet manifold.  Take it off, check for extra gasket hang over at the front near the distributor, trim it.  You will most likely find a gap at the edge of the head to block fill this with silicone.  Put a thick bead around the dizzy cut out.  Put some dowels in the inlet manifold bolt holes and locate the gasket.  Then put on the manifold and swap out the dowels for bolts.  Check you have the correct bolts in their location as there are 2 sizes, one length goeas around the carb holes, the other size around the outside