For Buick motors, TA Performance is the one stop shop. They are probably the only Buick shop around though... They make 4 versions of their aluminum heads from "you can't tell the heads at not stock if painted" to full on race. The basic heads are a bolt-on 50 HP to a stock motor. With a cam and matching intake, lots more. An example 455 Buick built by Motor Trend, .030 over with 9 to 1, TA SE1 stock Aluminum heads with a TA 234/244 at .500 cam and TA SPX single plane intake, 527 lb-ft at 4500 rpms and 513 HP at 5600 rpms. The engine makes 427 lb-ft of torque at 2200 rpms. Another 455 from a Buick forum, .030 over, 10 to 1, 288-94H cam, same SPX intake but the the SE1 heads ported from stock 290 cfm to 315 cfm. 575 ft-lb at 4600 and 556 HP at 5500. The stock Stage 1 in 1970 was rated at 370 HP, though it was probably a little more than that. Buick engines are not made for high rpms but they can make monster torque and good HP numbers below 6000 rpm. Above 6000 rpm, 900 HP without a blower is possible, if you have the $$$$. I have a 67' 430, the first year Buick dropped the nailhead V8s. In 70', the block was cast thicker and bored to make the 455. The strokes are the same for all BBB, 67' thru 76'. Btw... Edelbrock makes aluminum heads too, but they actually cost more.