Well, since it has 2 bolt mains, I don't think it's a Corvette LT1. You can also see what looks like an EGR valve on the side of the intake so it's probably a 70's or 80's motor. Did you check for the block casting date yet?

 

That engine looks to me like a 400. The main bearing caps are what to look at. They are much beefier than the 2-bolt caps on a 350. The sides of the 400 caps go into the block at an angle, whereas the 350's caps are straight up and down. That block also has the desirable untapped 3rd freeze plug, which some 400's have.

If you want a fast street/strip car on a budget, a 400 is the way to go. They make huge torque. I run a 400 in my '77 Z/28, and even though I still haven't sorted out all the bugs yet - the trans upshifts at 4900 instead of 5900 RPM - I've gone in the 12.40's at almost 110 mph in the heat at 3800 lbs. This is with a cheap Crane Blazer hyd. flat-tappet cam and stamped-steel GM rocker arms, and mildy ported stock Vortec heads, on BFG drag radials. With more grinding on the transmission governor weights to get my shift points up to 5700-5900 RPM, and some fine tuning of the combo, I feel an 11.90 is possible.

All I can say for sure is, after having a 400, I would not go back to a 350.

 

Check under the suffix code - there's a partial vin. If the second number there is a 5, you have a 1975 400cid engine, from an A or B body vehicle. ake off the heads. If the water holes are missing from between the bores, it's a confirmation. There are 2 and 4 bolt mains, and some did have two freeze plugs. Go behind the engine on the driver's side and check the casting number.

It's a great engine, if the block hasn't been misused. Be careful with part swaps, though, as there are differences that make a lot of sb parts incompatible without machining.

That 175hp engine can easily be boosted over 400 with a little planning and relatively inexpensively.

 

my experience with 400s .. 2 freeze plugs = 2 bolt mains .. 3 freeze plugs = 4 bolt mains .. also 2 bolt mains = thicker cylinder walls ..