Had 350 with stock efi on my 96 and took down 5.3's all day, don't knock old smallblock it was the engine of choice for most for many hotrodders and still today. Nothing wrong with old, you'll be there someday
And got half the milage.
1969 Chevy RCLB C10 350/TH400 SOLD
2007 Chevy RCSB 4.8 4x4 LS SOLD
2008 Chevy RCSB 5.3 4x4 LT SOLD
2010 Chevy CCSB 6.2 4x4 LT SOLD
2005 GMC CCLB DRW 6.6 Duramax 4x4 191,000 and counting
2013 FORD CCSB F350 6.7 Powerstroke 4x4