I'm also a "newbie," and I asked a similar question: will a same-era hydromatic bolt onto the back of the '49 straight eight? The answer was no, but the answer included a link to the web site of a company which makes block-to-bellhousing adapters for Buicks, fitting contemporary GM transmissions to staight-eight Buicks. I thought I had printed it, but if I did I can't find the hard copy---and I've looked all over this whole site for the past hour looking for my post and the answer I got, and I can't find it!
Maybe the person who was kind enough to reply to me will see this and reply to us both again.