Do you have a bootable SCSI CD drive for your Classic II? If you do, I may be able to help you get a copy of the 7.5.3 retail installer CD. PM me.
As indicated by equill, 7.5.3 may be a lethargic experience on a Classic II, I recall that mine was always more responsive under 7.1 and 7.0.1. (But there were enough good things in 7.1 to warrant going with it, in my opinion.)
As an interesting point of history: the retail installer for MacOS 7.5.3 can install on anything from a Mac Plus to a PowerMac 9500, including the Mac Portable. Possibly the most challenging install is putting it on a Mac Plus, which obviously requires an external hard drive to install it on. However the 7.5.3 installer must run from a minimum of a booted system 7.5.0, and 7.5 didn't fit on an 800k floppy. Also, the retail CD can boot any of the supported Macs with the exception of the Plus, which Apple knew about, but decided to ship, rather than fix. So you essentially need an *existing* 7.5.3 install on a second external hard drive just to boot with (presumably created by installing it onto a Mac greater than a Plus), then running the installer via either CD or by copying the CD to a hard drive and running the installer from that, or by running the installer on a Mac networked to the Plus via Localtalk. -The Localtalk install takes several hours.
The 7.5.3 installer polls the gestalt ID of the Mac it is installing on, and then runs a script to install only components that are intended fo that platform, unless you do a Universal install, which will install *everything*.
As indicated by equill, 7.5.3 may be a lethargic experience on a Classic II, I recall that mine was always more responsive under 7.1 and 7.0.1. (But there were enough good things in 7.1 to warrant going with it, in my opinion.)
As an interesting point of history: the retail installer for MacOS 7.5.3 can install on anything from a Mac Plus to a PowerMac 9500, including the Mac Portable. Possibly the most challenging install is putting it on a Mac Plus, which obviously requires an external hard drive to install it on. However the 7.5.3 installer must run from a minimum of a booted system 7.5.0, and 7.5 didn't fit on an 800k floppy. Also, the retail CD can boot any of the supported Macs with the exception of the Plus, which Apple knew about, but decided to ship, rather than fix. So you essentially need an *existing* 7.5.3 install on a second external hard drive just to boot with (presumably created by installing it onto a Mac greater than a Plus), then running the installer via either CD or by copying the CD to a hard drive and running the installer from that, or by running the installer on a Mac networked to the Plus via Localtalk. -The Localtalk install takes several hours.
The 7.5.3 installer polls the gestalt ID of the Mac it is installing on, and then runs a script to install only components that are intended fo that platform, unless you do a Universal install, which will install *everything*.