454 Chevy Big Block

Will a Chevy 454 Big Block fit in a 1969 G10 as easy as the 350?

I'm not sure but I would say not. The second gen doghouse is a pretty snug fit for the small block. Maybe Savage will chime in on this. If not PM him. He has a first gen with a 454 but I think he did a mid engine type build.

Side to side it will fit. not sure what you may run into towards the rad for space. May require a short water pump , maybe not. Definitely will need a cross flow set up for the radiator I'd think.

This is set back also but the width of the 2nd gen DH is original.

Like it was made for it (because it is!)......
BBC and SBC, along with straight sixes and 4.3 v-6's are all part of the chevrolet family of interchangeability, meaning that they all use the same three-point side mounts positioned at the same distances from the bellhousing face surface AND they all mount the same bellhousings and flywheels at standard distances and depths..... A 454 will literally bolt to the stock six cylinder mounts and can use the six's flywheel, clutch, bellhousing, starter and even the three-speed trans. Stock Chevelle/Nova exhaust manifolds will fit and there are no front length issues because the doghouse longer than any v-8 needs because of being for a six, and that extra length is forward....
I've done a 396 on the stock crossmember with a hanging t-350 mount and it fit like a glove.... I can't address doghouse issues since mine was a first gen..... You MAY have to load a BBC from the bottom, but I'm quite sure it will fit in there!

say don=?? as my memory is getting slow!!??- if I remember correctly? the 454 were externally balanced engines-requiring the external balanved crank balancer & a externally balanced flywhel & also flexplates-they were different from other 396/427/// 402 engines.

Yeah, probably so........The stuff will bolt together, but I hadn't thought about balancing issues......I personally would use an automatic trans with the appropriate flexplate.....
I also didn't mention that there are 2 flywheel sizes that require the correct starter.....The better one for better starting advantage is the one with more teeth (bigger). You can tell if this flywheel size is in use when the starter mounting bolts are staggered rather than side by side.... There are other issues when you mix and match chevy parts, even though they will bolt together.......

Mine got the staggered bolts on starter. Is that the big or small flywheel?? Not sure if its the one from motor,or came with PG??(that could be problem).  Pic of motor & custom dog
house.

staggered starter bolt pattern=Large flywheel-168??teeth.Now- since the 1965 vettes came with powerglides!!! that will work also!! I would get a heavyduty flexplate too!! From - experience!! I will remind all- if dealing with a pre 1971 origional engine?? these had = "Closed Chamber heads & pistins to fit!! 1971 & up were open chamber stuff=emissions--changed that for us!

The two different flexplate sizes will work with any of the automatic transmissions and engines as both sizes have all the bolt hole spaced the same...... The starter with staggered bolts fits the larger flywheel. (the engine blocks are drilled and tapped for either starter)