1.4 hp/ci? Realistic? Sure! My father told me there are three secrets to making horsepower. The first two are cylinder heads and third and most important.......cylinder heads!
So then.
Complete engine dis-assemble. Aftermarket flat top pistons 10.3-10.5:1 compression, ported aftermarket aluminum cylinder heads, valve springs, retainers, and locks to match the camshaft, single plane intake or ported Edelbrock airgap dual plane, 850 cfm 4-bbl, solid or hydraulic street roller camshaft (I prefer solids), hydraulic or solid roller lifters, bronze gear intermediate shaft, Comp Cams Pro-Magnum 1622-16 shaft rockers and custom length pushrods, high volume oil pump, Firecore50 distributor, the no name headers will work as I have tested the TTI $700 headers vs Summit Racing brand $130 headers and found 1HP average difference up to 6,000rpm. 3,000-3,300 rpm stall converter. Not a complete list but where I would start. I think you get the idea.