There's lots of threads on this subject but do yourself a favor and
make yourself a set of these...
...those I made '79 and still going. I made another one that's 1/2"
shorter that I haven't tried out yet but I'm sure it'll be a winner.
7/16-14 (coarse thread) one 6" and one 5+1/2"
Here's one in action...
http://www.panix.com/~alvinj/file12/guidepin.jpg
...the tansmission slid right up to the engine's locating pins with
the push of a foot. No kidding.
Do it however you want to but you won't catch me doing them
from underneath ever again...
http://www.panix.com/~alvinj/file12/hoist7m.jpg
...the engine hoist came in handy for engine pulling too.

And loading heavy stuff like windmill heads.
IMO that rear chain should have been behind the drain plug...
http://www.panix.com/~alvinj/file12/hoist8m.jpg
The 351w is well balanced and didn't -have- to have support.
But it won't hurt to put an 8 to 12 inch piece of 2x4 under the
oil pan and support it anyway.

I use that and a bottle jack.
Alvin in AZ
ps-
Rockauto: (I searched under '90 F250 parts truck for mine)
RhinoPac clutch kit 07057 $115 (LuK *diaphragm* pressure plate and disc)
RhinoPac slave S0707 $76
RhinoPac master cylinder M0706 $37
Dorman hydraulic line 628203 $28
Chris' Machine Shop:
~$25(?) to resurface the flywheel
McMaster-Carr:
6003 sealed ball bearing for clutch pilot bearing 6661K86 $22
Summit Racing:
ARP pressure plate bolts 250-2201 $11
ARP Pro-Series flywheel bolts 350-2802 $17