Engine is pulled - 273 rebuild or replacement 360 crate?

A hopped up 318 will be cheaper to build and be a stronger engine. It appears that your car is a 4 speed, so a 318 is already a neutral balance engine, where a 360 is not. Using a 360 means here comes a bigger bellhousing for the bigger flywheel needed. Then there's the special linkage you'd need to get from Brewer's. Build a mild 318 with an appropriate cam and some aluminum heads, KB167 pistons and a nice aluminum intake and send it with all the trans related stuff you already have. If you don't have an 8 3/4 rearend in it.....one may be coming soon, lol.