SID,
On my 61 f100 I reused the original passenger side manifold and blocked off the crosspipe opening with a piece of plate steel; the muffler attaches from there back to my body-side outlet.
On the Driver side I pulled the manifold from a parts 292, I picked up a few years ago, the flange is mounted forward and down at a 45 degree angle. From there I custom built the exhaust back to the body-side exit on the driver side.
I used 2.25" pipe because it was a close fit for the 2-bolt flanges I was able to find. I got this kit for $140 on sale:
https://www.speedwaymotors.com/Universal-Mild-Steel-Dual-Exhaust-Mandrel-Bend-Kit-2-1-4-Inch,25216.htmlAdded 2 Thrush mufflers that cost $24-25 each, something like this:
https://www.summitracing.com/parts/wlk-17649?seid=srese1&cm_mmc=pla-google-_-shopping-_-srese1-_-thrush&gclid=Cj0KCQjw9NbdBRCwARIsAPLsnFaTJ1FDfk4i8_9b7B3edUYzS9lRV6KzcdXUs_aRqpzHt2SD4nbCRXkaAhSiEALw_wcBSpent 2 Saturdays with a MIG using fluxcore 030 wire and had a spanky new exhaust system that I was quote $1200 to replace; All toll just under $200 and some elbow grease.
I will be more than happy to send you some pics if you like.