I looked at a pic of the 453 and the engine is transverse mount, driving hst pump with a belt. From the looks of it, I wouldn't shy from it. I take lots of pictures of where stuff goes, esp wires, when I do something like this first time. If you do it, think of other things that might be needed while engine is out, like other steel hydr lines with exterior corrosion though not yet leaking, and valve spool access might be much easier with engine out (might be worth changing spool seals if not done on your watch before) older machine…runs and drives good…does what you need it to…no computers…might be worth it. Good luck.