If this helps, here's the specs on the Olds version (turbo) from '63:
"1963 OLDSMOBILE JETFIRE - SPECIFICATIONS
JETFIRE-ENGINE: Turbo-Rocket V-8 • Fluid injection with turbocharger. Horsepower, 215 at 4800 R.P.M .• Torque 300 lb.-ft. at 3200 R.P.M .• Displacement, 215 cubic inches· Ultra high-compression, 10.25-to-1 ratio· Performance-tailored pistons, connecting rods, main bearings, distributor, fuel pump and coil· "
and the 'non-turbo" :155hp, 8.75-to-1 compression ratio, 215cu. in. displacement (This was also an aluminum blaock)
The Olds was different from the Buick:
"it had larger combustion chambers with flat-topped (rather than domed) pistons, six bolts rather than five per cylinder head, slightly larger intake valves, and the valves were actuated by independently-mounted rocker arms instead of shaft-mounted rocker arms. With an 8.75:1 compression ratio and a two-barrel carburetor, the Olds 215 had the same rated hp, 155 hp (116 kW) @ 4800 rpm, as the Buick 215, with 220 ft·lbf of torque at 2400 rpm. With a four-barrel carburetor and 10.25:1 compression, the Olds 215 made 185 hp (138 kW) @ 4800 rpm and 230 ft·lbf (312 N·m) (@ 3200 rpm.
The basic Buick/Olds 215 V8 went on to become the well known Rover V8, remaining in production until the 1990s. The Rover V8 however utilized Buick-style pistons, heads, and valvetrain gear."
And in '64 Olds redesigned their engines and they had no relation to the old ones.
NOW BUICK on the other hand. LOL. Okay, the famous 231 V6 (later to be known as the 3800 series) was also based on the Aluminum V8 structure. But that's irrelavant to what yyou asked.
I believe this might help:
"In 1964 Buick replaced the 215 with an iron-block engine of very similar architecture. The new engine had a bore of 3.75 in (95.5 mm) and a stroke of 3.40 in (86.4 mm) for a displacement of 300.4 cu. in. (4.9 L). It retained the aluminum cylinder heads, intake manifold, and accessories of the 215 for a dry weight of 405 lb (184 kg). The 300 was offered in two-barrel form, with 9.0:1 compression, making 210 hp @ 4600 rpm and 310 ft·lbf @ 2400 rpm, and four-barrel form, with 11.0:1 compression, making 250 hp @ 4800 rpm and 335 ft·lbf @ 3000 rpm.
For 1965 the 300 switched to a cast-iron heads, raising dry weight to 467 lb (212 kg), still quite light for a V8 engine of its era. The four-barrel option was cancelled for 1966, and the 300 was replaced entirely by the 350 in 1968."
I recently posted some pics etc (Of the Olds versions) but it's members only so can't link it.
The sixth bolt mentioned above that differentiates the Buick from the Olds was added to alleviate cooling problems believing it would seal the head better.
I hope this helps a wee bit.