Lyle was a big strong guy with good power and decent durability. 6'3" with a 76" reach and 215-220 Lbs. Tunney was a very technical boxer. He had good footwork, good defense, a good jab, and was accurate. Tunney was also very durable. He is one of only three Lineal HW Champs who were never stopped... Marciano and Bowe are the others. 6'1" with a 76" reach and about 190 Lbs. He used his reach well and he fought tall. He could also fight well an the inside if he had to. I think Tunney wins by clear decision. Lyle will have his moments. I see Lyle rocking Tunney, maybe even dropping him but Tunney eventually takes control of the fight and wins about 9 or 10 of the 15 rounds.
I don't think Tunney would be decked vs Lyle..his chin and overall abilities would be far superior to Jerry Quarry's and he would likely outbox and trounce Lyle over whatever distance they would fight. Tunney by a lopsided decision..ala Quarry-Lyle & Young-Lyle II.