IMHO, there wasn't an ideal single-engined attack plane in WW2. All of the candidates had significant flaws:
The Il-2 was very well armoured and armed to knock out tanks, but it was vulnerable to fighters. The Stuka G was in the same class, but less well protected.
The P-47 was a fighter-bomber rather than an attack plane; it could defend itself against enemy fighters but, although very tough by fighter standards, it had nowhere near the protection of an Il-2, and it was generally ineffective against tanks - its guns couldn't hurt them and its bombs couldn't hit them (with the odd lucky exception). IMO, a complete all-round attack aircraft MUST be able to deal with tanks.
The Hurri IID could hurt tanks (until the Tiger came along) but was pretty defenceless against both fighters and flak.
The Yak-9T with that NS-37 could hurt tanks - all of them - and could defend itself against fighters, but it wasn't armoured against ground fire because that wasn't its purpose in life.
I spent a little time on my discussion forum a while back specifying an ideal WW2 single-engined attack plane. It needed to have fighter-like performance and hadling but good protection (including an air-cooled engine) and the ability to carry one powerful cannon for anti-tank use (the only reliable way to nail 'em...). The configuration I came up with was a twin-boom pusher with a radial engine and a cockpit right forward for best forwards and downwards visibility (think DH Vampire with a prop). The gun would run right through the centre of the fuselage with the barrel between the pilot's legs

to avoid attitude changes on firing. Supplementary guns could be mounted on the cockpit sides. The wing would be basically a high-speed fighter type, but with extensive slots and flaps for semi-STOL performance in rough fields and good lifting ability of bombs and rockets. Undercarriage would be tricycle, long-stroke and heavy duty. The cockpit would be an armoured bathtub.
A modified version (less armour, more fuel, 3x20mm) could have made a good naval fighter-bomber.
Tony Williams
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