Is 426ci 360 a small block?

Switching to the TTI headers gained us 12 HP peak and 1 lb-ft and 1 hp average gain from 3000-6000 rpm. And they only cost an additional $520.

So we switched carbs from the 850 Mighty Demon (column 1) to 1050 RS Race Demon (column 2) and then the last pull of the day w/ 2" spacer (column 3).

RPM...........(1) TQ/HP............(2) TQ/HP...........(3) TQ/HP

3000.............434/248...............456/260.............450/257
3200.............447/273...............466/284.............466/284
3400.............442/286...............477/307.............480/311
3600.............453/310...............491/336.............490/336
3800.............451/327...............484/350.............496/359
4000.............454/346...............494/376.............499/380
4200.............494/394...............511/409.............518/414
4400.............511/428...............536/449.............532/446
4600.............529/463...............547/479.............546/478
4800.............538/491...............547/500.............554/507
5000.............543/517...............549/522.............557/530
5200.............536/531...............547/541.............543/538
5400.............530/545...............533/548.............535/550
5600.............517/551...............530/565.............528/563
5800.............512/556...............514/567.............519/573
6000.............506/578...............504/575.............510/582
6100.............499/579...............501/582.............504/585
6200.............487/574...............491/579.............497/587
6300.............485/582...............593/591.............497/596
6400.............481/586...............480/585.............486/592
6500.............470/581...............470/582.............477/590
6600.............463/582...............462/580.............466/586
6700.............443/564...............455/581.............457/583

I call it a 426 because it sounds better, but is actually 4.042" bore by 4.125 stroke for 423.5 ci, The dog is now only making 1.41 hp/ci on 91 octane.