If you have an I&T manual (you said earlier?) 'lash' would be under valve adjustment or similar for the walk thru' and spec'd with your engine's other details in the front pages. Valve cover comes off ... (btw, look for foreign matter, sludge in/under it) ... and you'd want any ol' feeler gauge set and a new VC gasket on hand.
btw: you may not be confident at first when positioning the crankshaft (twice during, just turning by hand with s-plug
s out) but the instructions are in pretty plain English (if I'm not always

) so ... IMO 2-3 of 5 on elbow grease or difficulty even if not much experience under vehicle hoods. (compression test ~ a 1, btw)
Possible causes for 'lean'/weak idle besides incorrect float level are carb or manifold gasket leak, plugged pilot jet, throttle shaft leak, vacuum leak to distributor advance biz, even stuck advance weights that don't ******. btw, at 900 rpm, needing the choke does mean something is 'up with that'. :laughing:
General bits from me, and not make/model-specific. As always, expect much good Ford help from TBN'ers who wrench & ride 4xxx's vs uh ... just envy someone else's.
