Worth it to build my 273?

Put the 273 under the bench. start with a early 360 or 340 . 75 and newer 360's are weak and should only be used if you can't find an early one. Also stay with a lower mold number. your chances for more concentric cylinders in a sonic test is better.The more even your walls are the less deformity under heat and stress. 340-1 being the best 340-2 next and so on.