I have a question abotu a truck 5.0

It is a 2 barrel EFI type intake system and I wanted to know what the engine specs like compression, valve sizes, cam size, chamber CC and so on. If you guys know the HP/Torque rating it would be great, Im considering putting this engine in my 66 mustang and posted it here since i believe it came out of an 80's truck, the only numbers i could really find were on the back of the engine plate which read:

D90 E6A373
19-BA

A few things i also were considering where putting the heads on my 66 289 if the valves are big enough to make a differance over the 289 2v heads. To compinsate for the larger Chambers (56cc???) compares to the 289 54cc heads i was plannning on getting them machined. Or possible putting my 289 heads on the 5.0 block to increase compression.

If i use the 5.0 block, i would be putting my comp cams .456 cam, edelbrock performer and roller timing chaine, headers, and holley carb, and 66 water pump and timing chain cover to use my mechanical fuel pump and to use my old radiator as well since the water pump outlets are on different sides.

Thanks guys

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Under Construction 66 Coupe

The casting number for the heads will be below the intake ports in the lifter galley area. They are hard to see when the heads are installed.