273 to 383 engine swap?
Yes and no. Yes, it can be done, Dodge did it at the factory in some GTS darts. No, you probubly dont want to try it. It is a huge ammount of work. You will need to change the "K" member first so you can mount the engine(finding a big block A-body k member is difficult) you need to change the torsion bars, brakes to accomodate the heavier engine, cut holes in the fenderwells to run headers(unless your incredibly lucky and find original 383 manifolds) change rear end to an 8.75in unit or dana 60 and add sub frame connectors to put up with the extra torque, re-locate the trans crossmember,to accomodate the longer big block trans and hand fab your exhaust. All in all, A 318/340/360 would be the way to go if your interested in more power. These engines are the same size as the original 273. The car is going to lose value with an engine swap, be sure to keep the original engine for later restoration.
Agree w/ Horseapple...though I don't think Dodge tried it until '67 Dart which is slightly different engine bay. But the same issues as mentioned would need to be addressed. My 68 Dart was a 273 and now 383.
You might want to check w/ Schumachers, www.engine-swaps.com as they might save you the K frame swap (though not sure how popular the '66/383 deal) would be that they may have created mounts for it. TTI also does some very tight header configurations that may avoid fender wall cuts...did on my Dart. Definetly need to upgrade rearend to 8 3/4.
Good luck
You might want to check w/ Schumachers, www.engine-swaps.com as they might save you the K frame swap (though not sure how popular the '66/383 deal) would be that they may have created mounts for it. TTI also does some very tight header configurations that may avoid fender wall cuts...did on my Dart. Definetly need to upgrade rearend to 8 3/4.
Good luck



