Allright, heres my take on it. During the late 60s-early 70s buicks were not considered valuable or even popular. As they had an image of the squishy upscale family-type car, no one wanted them for HP or hot rodding. As such, they got used, and sent off to the junkyard. Many of the Buicks from that generation had 350s, some with 2v per and some with 4v per cylinder. Your 430 is not a common block, and due to the gobs of torque to old buick blocks liked to make, they were beat into the dirt. Think of a kid with 500 ft-lbs for 800$. Not a good combo. As such, they were trashed on the streets then sent to the yard. Try rebuiltautoengines.com They seem to have 455s rebuilt, maybe you can get a 430. Also try Jasper. they seem to find some strange engines. Sorry, but thats all i can tell you.