Don...Unless you're going 4 wheeling with a 2 ton load in the back of your Panel...MII IFS is more than robust enough for what you need...remember somebody drove your '46 around with it's stock suspension for almost 60 years and it still works! Also remember that your original truck had a 216 engine that weighed or weighs nearly 700 lbs...I assume you're going to swap a SB Chevy or its equvalent...they weigh under 600 lbs.
If you're still concerned box your frame, find an original MII IFS with Struts.
I have original MII IFS in both my 49 & 52 Suburbans (which weigh 3800 lbs)...outstanding.
