[Accelo]

All double heads are not Fuel injection heads.
The same double hump castings were used on everything from 327’s 275HP and up. All double hump heads came with either 1.94 or 2.02 valves. Only the lowly 250hp and some others like the 310hp had the small valve heads (1.74). The double hump heads are not rare at all.
The 300hp also had the same casting number and double hump identifications as their 2.02 big brothers. The 300hp has the 1.94 intake valves. Only the 350hp and 365 and 375hp motors came with 2.02 valves.
2.02 heads also had the side of the chamber, nearest to the intake, machined/relived from the combustion chamber from the factory. If you retrofit 2.02 valves to these heads and do not relieve the chambers you actually cut the port flow not increase it. It's mostly old inaccurate lore from long ago lives on never be replaced.
That said I would like to see a 327 with a modern set of Vortec heads installed on it. Would be interesting to see how it would run with some better flowing heads. They would drop the compression slightly as they have 67cc Chambers not the 64cc chambers like the original heads.
If you raced an all-stock 365hp 327 and a stock truck 5.3L in the exact same vehicles the modern truck motor would be faster. The 5.3L makes way more torque. And if you installed an equivalent cam in the truck motor, as the 365/375hp 327 it would be even worse for the 327.
For the record I have a 340hp 327. It is a great motor. But GM has leaned a bit since then.
Cheers.