I just ran these numbers thru the Wallace CR calculator.
428 +.030, 98cc heads, 3.8cc valve reliefs(Auto-Tec), .039 x 4.3 gaskets, .000 deck height
CR = 8.98:1.
Just a slight cut off the heads will put it over 9:1. That's plenty for a pump gas engine today.
Compression Ratio Calculator - Wallace Racing
You can also order the Auto-Tec pistons, with the pin location moved, at no charge, to give you zero deck height without cutting the deck down.
But, for the same $$, I'd still go with a 4.21 or 4.25 stroke.
Another good suggestion using the pistons to both raise compression and move the pin height so you do not have to cut the deck.
However, the stumbling block is again the small heads. Using the Wallace calculator to estimate HP, and engine RPM, versus head flow: Estimate Horsepower from Intake Airflow
shows a limited RPM range as would be expected.
The small valve heads will probably flow 180 CFM (at best) at 28" of water at a maximum lift of .500", so this number was used.
4.25" stroked (most common), .030" overbore, 400CI is 461 cubes. Setting the calculator specs on the Street/Strip mode, the calculator says 341HP at an RPM range between 2,570 and 4,070 RPM's. Choosing the Typical Race Engine mode produces more HP at 370HP, but the RPM numbers remain the same; 2,570 to 4,070 RPM's.
The 4.21" stroke yields a 455CI engine. Same 341HP, but the decrease in stroke yields higher RPM numbers; 2,624 to 4,124 RPM's in Street/Strip mode with the RPM's being the same in Race mode and HP increasing to the same 370HP above.
The 4.00" stroke, .030" over yields a 433CI engine. Same 341HP, but the decrease in stroke again yields higher RPM numbers; 2,833 to 4,333 RPM's. In Race mode, same 370HP with the higher RPM numbers.
What can be seen is that the stroke affects the RPM power band range. It does not mean you won't spin the engine to higher RPM's, it just shows that the larger the stroke (and cubic inches), the lower the power range drops using the smaller heads - and Pontiac engineers knew this as the 455 used torque over HP to move the big cars.
Just for fun, lets use an Edelbrock D-port head that flows 251 CFM's at .500" lift at 28" of water for comparison using the 4.25" stroked 461 engine. WOW! In the Street/Strip mode, you get 476HP in an RPM range of 4,176 to 5,676 RPM's. The increase in airflow boosts power up 135 horsepower and raises the power band into the mid-upper RPM's. Race mode simply increases the HP to 516HP with same RPM band.
What is not given of course is compression ratio,cam selection, intake/carb, or exhaust as this is taken into consideration through the selection of choosing which calculator mode you want the engine use to fall into - so this is a generalization at best, but it works for our example.
The point of this exercise is to simply show how head flow affects HP as stroke affects the powerband at which HP is made. The key ingredient in maximizing HP, no matter what size your engine is, is air flow, or CFM's. Knowing what the heads/intake/carb will flow can then be matched to the cam selection and desired use of the engine. You can also have too much air flow just as you can have too much cam or carb.