The cam specs may have been the same between the 248 and 273, but the cams can't be interchanged between A and LA. The port layouts are different, therefore the cam lobes are sequenced differently. Same core, different lobe layout.
The duration was the same. I haven't been able to come up with lift figures for the poly 318 four barrel. 273, of course, is .415/.425. Very mild cam, actually.
I've heard people say the 273 hi-po had a "hot solid lifter cam." But it wasn't much hotter than the two barrel cam, which was also a solid lifter cam - same as every A motor ever built except the 59 Dodge 325 (or 326) poly, which was just a .040 over 318. Dodge was still exclusively a mid-priced car in 59, so had to have a bigger motor than the Plymouth. Besides the extra eight cubes, the Dodge poly also got hydraulic lifters. Next year, Chrysler Corp said the heck with this and dropped the 326 poly; was 318 from then on.
And, talk about hp ratings, the extra eight cubic inches of the 59 Dodge motor somehow bumped the power up to 255 - still with a two barrel carb, single exhaust and the same compression ratio as the 318 poly. Twenty five hp from eight cubic inches. Pretty good trick. . . .
