You should really CC them heads to determine the Combustin Chamber volume. I suspect they could be 118cc rather then 122 but seems to me from many reports that both the 781 and 049 heads could have either a 118 or a 122cc volume. The 73 454 ci engine is an ideal candidate for making power. Although they came with flat tops .025" in the Hole and have approx an 8.2 Static compression. You can up the compression using the flat tops by running an older set of 100CC heads; OR:
If you have a 118cc combustion chamber volume the Speed Pro L2465F with a composite .039" gasket will give a 9.5:1 Static compression with a .064 quench and better yet a 10:1 Static compression with a Steel .019" Shim gasket to yield a .044" quench.
If the CC Volume is greater you have 3 alternatives: 1/ get a piston with higher dome - not recommended as spark and combustion travel is hampered. 2/ "0" deck the block and run the .039" composite gasket - recommended. 3/ Shave the 122 Heads to say a 116 cc Volume is also recommended with the L2465 Pistons.
Whether Decking the Block or Milling the heads you must be more wary of the Piston to Valve Clearances Vs Cam choice and in both incidents will change the fitting of the intake manifold and push rod lengths. From my experiences, "0" Decking and using a .039" thick gasket was not enough variance to effect either the Intake fitting or Push Rod length.
By stroking the engine - increasing the volume sweep, that is using a Crank with a longer stroke you are compressing a greater volume thus increasing the CI of the engine to 496 and the Static compression and can run a flat top piston which benefits flame and combustion and reduces ping; however, I have never had a ping problem running a 9.5 to say a 10.25:1 454 with the L2465F piston by keeping the Dynamic Compression below 8.2 and that is determined by cam choice.
A 278H 10 or 12 cam would be an excellent choice for a 9.5:1 Static Compression 454ci engine.
Suggest you download P Kelleys DCR Calculator here: http://www.empirenet.com/pkelley2/DynamicCR.html