May purchase 65 Barracuda

Does it have a tach? That would be an "S" code..is there a 2 under the 'C' on the fender tag? Best thing for these cars is better exhaust IMHO (true duals with no Y pipe) followed by disc brakes up front and a dual circuit Master cylinder. If you want to delve a little deeper, that single plane intake is not the best. A modern dual plane would work better but won't fit those heads unless you alter the bolt hole angles in the AL intake, it's been done with a hand drill and some hardened washers under the smallish intake bolts of the 64-65 heads. Some modern "302" code heads will get you hardened valve seats, a similar quench head and the standard bolt angle for any aftermarket intake. I like the Performer 318/360 on the small 273 as well as the LD4B small port high rise dual plane. Most of the other aftermarket intakes have 340/360 port sizes that will fit but will not match up and will possible leak if you dont use the correct intake gasket. The high compression pistons on this engine will suffer under todays crap gas. You can help with some thicker .060 head gaskets but not the best option. A slant will run on most anything flammable with its low sub 8 CR. The 4bbl 273 is at the opposite end: needs good gas to run safely, ping will kill. A '67 318 is a great motor to look for as its really a bored out 273 with standard bolt angle heads and the same crank register (automatic) as well as balance (manual). It has much more low end torque and is just shy on peak HP of the 273/4bbl. You can move the top end and cam and lifters/valvetrain over to the 318 and make a cheap 318/4bbl or get a better matched solid cam, or keep stock hydraulic valvetrain of 318 and get a small hydraulic cam. Just don't go crazy on the cam as the small displacement makes the performance cams "peaky" giving a soft bottom and a narrow power band. The 360 with the same cam will be totally different.