The problem that I ran into when I did my LS swap was not just getting mounts to install the motor, but also want to consider your headers, trans mount oil pan and engine accessories. I also used the Dirty Dingo adjustable mounts, but found I had a difficult time finding headers that both fit, and provided good ground clearance. I would look into someone that will sell you individual components so that you could buy engine mounts first, and find maybe a cheap set of manifolds that fit to get you going. Then as you have more cash, you can buy headers and know they will fit the way you want.
I did exactly this when I built my 1968 Camaro. I opted for the Holley mounts, and then made my other components fit around them. I never ended up buying the headers, but I liked knowing that if/when I did buy them, it would be a drop in deal.