361-----383----400 all are called the B series Lo Block. Almost every part is interchangable. The 361 has a 4.12bore . The 383 has a 4.25 bore and the 400 has 4.34 bore . All have the same stroke 3.38 I dont know how far You can bore the 361,but it would certainly be worth looking into. I would think You could build a hard hitting motor out of what You have. If You refer back a couple weeks to my thread comparing a 302 ford , 305chevy, 318 chrysler,You will see the 318 made 349 horsepower. I would think 400 plus horsepower is not out of the question with the 361.If I had had that car with that motor for 27 years,thats what I'd build. There is a Direction Racing Manual that You can get from Chrysler that would be very helpful to you, You can buy just about everything You need across the counter At your local Dodge/Chrysler store.Hope You can buy your parts wholesale or know someone who will get them for you. Good Luck!!