I just put in one of those L31-R in my 74 chevy stepside man. Just ask if you have any questions about the swap. Ill post a pic of mine in my truck Im taking it out for the first time since the swap tomarrow!!!
The L31-R Vortec is by far the way to go. Vortec heads are a verry popular head for budget builders. If you do some head work and a cam swap you can make great power with the vortec engine. Vortec heads, 4 bolt mains, roller camshaft, Higher Compression Ratio of 9.4:1..The 290 HP Crate Engine has lame heads, flat tapped cam, low 8.5:1 compression ratio. Get the Vortec L31-R 3/4 ton heavy duty vesion from Jegs its only like 1829.99$+free shipping and no tax no core charge Summit sells the same engine for 2158.95+100$ core charge+shipping. Actually every other place sells it for much more than jegs and they all charge shipping. I have no clue why jegs is so much cheaper.
1986-2000 style block, 4 bolt mains (No Fuel Pump Provision)
1pc rear seal nodular iron crankshaft
Powdered metal connecting rods
Hypereutectic pistons 9.4:1 compression Ratio
Hydraulic roller camshaft: Int Lift .414", Exh Lift .428", Int Duration @.050" 191, Exh Duration @ .050" 196, Lobe Centerline-111
Vortec cylinder heads - 64cc, 1.94'' intake valve, 1.50'' exhaust valve
Also includes: Oil pan, timing cover, valve covers, harmonic balancer