The adapter does not take up much space and the smaller starter is a plus. I have an AOD and 5.0 SBF in my '54 there is no issue with floor clearance,is your '56 a Ford-O-Matic ? Check out the installation here: https://www.transmissionadapters.com/ford_y_block.htm The AOD to transmission cross member mount is an ANCHOR 2253 about $10 at O'Reillys.